リモートのCentOS Linux 8ホストにインストールされているパッケージは、CESA-2020: 4743のアドバイザリに記載されている脆弱性の影響を受けます。

  - Squid: リクエストの不適切な入力検証により、プロキシ操作が可能になります（CVE-2019-12520）

  - Squid: addStackElementのoff-by-oneエラーにより、ヒープバッファオーバーフローおよびクラッシュが引き起こされます（CVE-2019-12521）

  - Squid: URIプロセッサでの不適切な入力検証（CVE-2019-12523）

  - Squid: url_regexでの不適切なアクセス制限により、セキュリティバイパスが発生する可能性があります（CVE-2019-12524）

  - Squid: URN処理におけるヒープオーバーフローの問題（CVE-2019-12526）

  - Squid: FTPゲートウェイの情報漏洩の問題（CVE-2019-12528）

  - Squid: Proxy-Authorizationヘッダーの領域外読み取りは、DOSを引き起こします（CVE-2019-12529）

  - Squid: cachemgr.cgiにおけるサービス拒否（CVE-2019-12854）

  - Squid: URIプロセッサでのバッファオーバーフロー（CVE-2019-18676）

  - Squid: HTTPリクエスト処理におけるクロスサイトリクエスト偽造の問題（CVE-2019-18677）

  - Squid: HTTPメッセージ処理におけるHTTPリクエスト分割の問題（CVE-2019-18678）

  - Squid: HTTP Digest認証における情報漏洩の問題（CVE-2019-18679）

  - Squid: cachemgr.cgiに対するホストパラメーターのHTMLが不適切に処理されると、安全でない挙動が発生します（CVE-2019-18860）

  - Squid: TLSハンドシェイクにおけるDoS（CVE-2020-14058）

  - Squid: HTTPキャッシュに対するリクエストスマグリングおよびポイズニング攻撃（CVE-2020-15049）

  - Squid: 不適切な入力検証により、DoSが発生する可能性があります（CVE-2020-24606）

  - Squid: HTTPリクエスト処理における不適切な入力検証の問題（CVE-2020-8449）

  - Squid: リバースプロキシ構成におけるバッファオーバーフロー（CVE-2020-8450）

Nessus はこれらの問題をテストしておらず、代わりにアプリケーションの自己報告されたバージョン番号にのみ依存しています。

新版本更新 - squid 4.9 请注意，Tenable Network Security 已直接从 Fedora 更新系统网站提取上述描述块。Tenable 已尝试在不引入其他问题的情况下尽可能进行了自动整理和排版。

远程 CentOS Linux 8 主机上安装的程序包受到 CESA-2020: 4743 公告中提及的多个漏洞的影响。

  - squid：请求中的不当输入验证允许代理操控 (CVE-2019-12520)

  - squid：addStackElement 中的差一错误允许堆缓冲区溢出和崩溃 (CVE-2019-12521)

  - squid：URI 处理器中的输入验证不正确 (CVE-2019-12523)

  - squid：url_regex 中的不当访问限制可能导致安全绕过 (CVE-2019-12524)

  - squid：URN 处理中的堆溢出问题 (CVE-2019-12526)

  - squid：FTP 网关中存在信息泄露问题 (CVE-2019-12528)

  - squid：Proxy-Authorization 标头中的越界读取可造成 DoS (CVE-2019-12529)

  - squid：cachemgr.cgi 中的拒绝服务 (CVE-2019-12854)

  - squid：URI 处理器中的缓冲区溢出 (CVE-2019-18676)

  - squid：处理 HTTP 请求过程中发生跨站请求伪造问题 (CVE-2019-18677)

  - squid：处理 HTTP 消息过程中发生 HTTP 请求拆分问题 (CVE-2019-18678)

  - squid：HTTP 摘要式身份验证中发生信息泄露问题 (CVE-2019-18679)

  - squid：未正确处理 cachemgr.cgi 的主机参数中的 HTML 可导致不安全行为 (CVE-2019-18860)

  - squid：TLS 握手中的 DoS (CVE-2020-14058)

  - squid：针对 HTTP 缓存的请求走私和中毒攻击 (CVE-2020-15049)

  - squid：不当输入验证可导致 DoS (CVE-2020-24606)

  - squid：HTTP 请求处理过程中存在不当输入验证问题 (CVE-2020-8449)

  - squid：反向代理配置中存在缓冲区溢出 (CVE-2020-8450)

请注意，Nessus 尚未测试这些问题，而是只依据应用程序自我报告的版本号进行判断。

远程主机上安装的测试产品版本低于测试版本。因此，如公告 ALAS2-2020-1486 所述，该主机受到多个漏洞的影响。

  - 此漏洞使远程攻击者能够在易受攻击的 Squid Software Foundation Squid 3.5.27-20180318 安装版本上拒绝服务。无需认证即可利用此漏洞。
    具体缺陷存在于 ClientRequestContext: : sslBumpAccessCheck() 中。构建的请求可触发空指针取消引用。攻击者可利用此漏洞对系统的用户造成拒绝服务情况。是 ZDI-CAN-6088。(CVE-2018-1172)

  - 在 Squid 4.10 之前的版本中发现问题。它允许构建的 FTP 服务器触发堆内存中敏感信息（例如，与其他用户的会话或非 Squid 进程相关的信息）的泄露。(CVE-2019-12528)

  - 在 Squid 2.x、3.x 及 4.x 至 4.8 版本中发现问题。由于不正确的数据管理，导致在处理 HTTP 摘要式身份验证时容易发生信息泄露。Nonce 令牌包含位于堆内存分配中的指针的原始字节值。此信息会减少 ASLR 保护，并且可能会协助攻击者将内存区域隔离至目标，从而实现远程代码执行攻击。
    (CVE-2019-18679)

  - 在 Squid 4.10 之前的版本中发现问题。由于不正确的缓冲区管理，导致远程客户端可在充当反向代理的 Squid 实例中造成缓冲区溢出。(CVE-2020-8450)

请注意，Nessus 尚未测试此问题，而是只依赖于应用程序自我报告的版本号。

在 Squid 代理快取伺服器中發現多個安全性問題，可導致繞過安全性篩選器、資訊洩漏、任意程式碼執行或拒絕服務。

遠端 Redhat Enterprise Linux 8 主機上安裝的套件受到 RHSA-2020: 4743 公告中所提及的多個弱點影響。

  - squid：要求中的不當輸入驗證可造成 Proxy 操控 (CVE-2019-12520)

  - squid：addStackElement 中的差一錯誤可造成堆積緩衝區溢位和損毀 (CVE-2019-12521)

  - squid：URI 處理器中存在不當輸入驗證 (CVE-2019-12523)

  - squid：url_regex 中的不當存取限制可能導致安全性繞過 (CVE-2019-12524)

  - squid：URN 處理中存在堆積溢位問題 (CVE-2019-12526)

  - squid：FTP 閘道中存在資訊洩漏問題 (CVE-2019-12528)

  - squid：Proxy-Authorization 標頭中存在超出邊界讀取，可造成 DoS (CVE-2019-12529)

  - squid：cachemgr.cgi 中存在拒絕服務問題 (CVE-2019-12854)

  - squid：URI 處理器中存在緩衝區溢位問題 (CVE-2019-18676)

  - squid：HTTP 要求處理過程中存在跨網站要求偽造問題 (CVE-2019-18677)

  - squid：HTTP 訊息處理中存在 HTTP 要求分割問題 (CVE-2019-18678)

  - squid：HTTP 摘要式驗證中存在資訊洩漏問題 (CVE-2019-18679)

  - squid：未正確處理 cachemgr.cgi 主機參數中的 HTML，可導致不安全的行為 (CVE-2019-18860)

  - squid：TLS 交握中發生 DoS (CVE-2020-14058)

  - squid：針對 HTTP 快取的要求走私和毒害攻擊 (CVE-2020-15049)

  - squid：不當輸入驗證可導致 DoS (CVE-2020-24606)

  - squid：處理 HTTP 要求時會發生不當輸入驗證問題 (CVE-2020-8449)

  - squid：反向代理設定中有緩衝區溢位問題 (CVE-2020-8450)

請注意，Nessus 並未測試這些問題，而是僅依據應用程式自我報告的版本號碼作出判斷。

遠端 Rocky Linux 8 主機已安裝受到多個弱點影響的套件如 RLSA-2020:4743 公告中所提及。

  - 在 Squid 4.7 以及之前的所有版本和第 5 版中發現一個問題。Squid 會在接收要求時檢查其快取，以確認是否可以提供回應。它透過對要求的絕對 URL 進行 MD5 雜湊來實現這一點。
    如果找到，則爲要求提供服務。絕對 URL 可包含針對特定通訊協定解碼後的 UserInfo (使用者名稱和密碼)，此解碼後的資訊會附加在網域之前。攻擊者可藉此提供具有特殊字元的使用者名稱來分隔網域，並將 URL 的其餘部分視為路徑或查詢字串。攻擊者可先使用編碼的使用者名稱向其網域提出要求，然後當解碼為確切 URL 的目標網域要求傳入時，程式會提供攻擊者的 HTML，而非真正的 HTML。若 Squid 伺服器也充當反向 Proxy，這會允許攻擊者存取只有反向 Proxy 可以使用的功能，例如 ESI。(CVE-2019-12520)

  - 在 Squid 4.7 及之前版本中發現一個問題。Squid 剖析 ESI 時，會將 ESI 元素保留在 ESIContext 中。ESIContext 中有一個緩衝區，用於保留 ESIElements 堆疊。剖析新的 ESIElement 時，它會透過 addStackElement 進行新增。 addStackElement 會檢查此緩衝區中的元素數，但會差一，從而導致堆積溢位元素為 1。此溢位發生於相同結構內，因此不會影響相鄰的記憶體區塊，只會在處理時導致當機。
    (CVE-2019-12521)

  - 在 Squid 4.9 之前版本中發現一個問題。處理 URN 要求時，程式會提出對應的 HTTP 要求。此 HTTP 要求不會經過傳入 HTTP 要求所經過的存取權限檢查。這會造成所有存取權限檢查被略過，並且允許存取受限制的 HTTP 伺服器，例如，攻擊者可連線至僅在 localhost 上接聽的 HTTP 伺服器。(CVE-2019-12523)

  - 在 Squid 4.7 及之前版本中發現一個問題。處理使用者發出的要求時，Squid 會檢查其規則以查看是否應拒絕該要求。Squid 依預設使用可封鎖快取管理員存取權限的規則，而該快取管理員可爲維護者提供伺服器詳細資訊。此規則是透過 url_regex 實作。url_regex 規則 URL 的處理常式會解碼傳入的要求，這讓攻擊者可以對其 URL 進行編碼，以繞過 url_regex 檢查，並取得對封鎖資源的存取權。(CVE-2019-12524)

  - 在 Squid 4.9 之前版本中發現一個問題。Squid 中的 URN 回應處理受到一個堆積型緩衝區溢位問題的影響。當從遠端伺服器接收資料以回應 URN 要求時，Squid 無法確保回應能夠放入緩衝區。這會導致由攻擊者控制的資料在堆積中溢位。(CVE-2019-12526)

  - 在 Squid 4.10 之前版本中發現一個問題。它允許特製的 FTP 伺服器從堆積記憶體觸發敏感資訊洩漏，例如與其他使用者工作階段或非 Squid 處理程序相關的資訊。(CVE-2019-12528)

  - 在 Squid 2.x 至 2.7.STABLE9 版、3.x 至 3.5.28 和 4.x 至 4.7 版中發現一個問題。將 Squid 設定為使用基本驗證時，它會透過 uudecode 剖析 Proxy-Authorization 標頭。
    uudecode 透過反覆輸入並檢查其表格來決定將要解碼的位元組數量，然後使用該長度開始解碼字串。沒有任何檢查確保其計算的長度不會大於輸入緩衝區。這也會導致相鄰記憶體被解碼。除非 Squid 維護者已設定錯誤頁面上的使用者名稱顯示，否則攻擊者無法擷取解碼後的資料。(CVE-2019-12529)

  - 由於字串結尾錯誤，Squid cachemgr.cgi 4.0 至 4.7 可能會存取未配置的記憶體。在具有記憶體存取保護機制的系統上，這可造成 CGI 處理程序意外終止，進而導致所有使用該處理程序的用戶端拒絕服務。(CVE-2019-12854)

  - 在 Squid 3.x、4.x 至 4.8 版本中發現一個問題。由於輸入驗證不正確，程式會發生堆積型緩衝區溢位，從而導致使用 Proxy 的所有用戶端拒絕服務。此弱點發生在正常安全性檢查之前，因此屬於高嚴重性問題。任何可連線至 Proxy 連接埠的遠端用戶端皆可透過特製的 URI 配置輕鬆執行攻擊。(CVE-2019-18676)

  - 使用 append_domain 設定時，Squid 3.x 以及 4.x 至 4.8 版中會產生問題 (因為附加字元未與主機名稱長度限制正確互動)。由於訊息處理不正確，它可以錯誤地將流量重新導向至不應傳送的目的地來源。
    (CVE-2019-18677)

  - 在 Squid 3.x、4.x 至 4.8 版本中發現一個問題。它允許攻擊者透過前端軟體將 HTTP 要求走私至 Squid 執行個體，然後由該執行個體以不同方式分割 HTTP 要求工作流程。所產生的回應訊息會在任意 URL 上使用攻擊者控制的內容損毀 (用戶端和 Squid 之間的) 快取。僅影響攻擊者用戶端和 Squid 之間的軟體。對 Squid 本身或任何上游伺服器都沒有影響。此問題涉及標頭名稱和冒號之間含有空格的一個要求標頭。(CVE-2019-18678)

  - 在 Squid 2.x、3.x 及 4.x 至 4.8 版本中發現一個問題。由於資料管理不正確，處理 HTTP 摘要式驗證時容易發生資訊洩漏。Nonce token 包含堆積記憶體配置中指標的原始位元組值。此資訊會降低 ASLR 保護，並可協助攻擊者隔離作為遠端程式碼執行攻擊目標的記憶體區域。
    (CVE-2019-18679)

  - 使用特定的網頁瀏覽器時，Squid 4.9 之前版本會將 host (即主機名稱) 參數中的 HTML 錯誤處理為 cachemgr.cgi。(CVE-2019-18860)

  在 4.12 版之前和 5.0.3 之前 5.x 版的 Squid 中，發現一個問題。由於使用了可能危險的函式，Squid 和預設的憑證驗證協助程式在為 HTTPS 開啓連線至受攻擊者控制之伺服器的 TLS 連線時，容易遭受拒絕服務攻擊。這是因為無法識別的錯誤值會對應至 NULL，而之後的程式碼預期每個錯誤值對應至有效的錯誤字串。(CVE-2020-14058)

  在 4.12 版之前和 5.0.3 之前 5.x 版的 Squid 中，發現 http/ContentLengthInterpreter.cc 中有一個問題。可針對 HTTP 快取發動要求走私和毒害攻擊。用戶端會傳送具有 Content-Length 標頭的 HTTP 要求，標頭中包含 + \- 或長度欄位值或含有不常見的 shell 空白字元前置詞。(CVE-2020-15049)

  - 4.13 之前和 5.0.4 之前的 5.x 版 Squid 允許一個可信節點在處理特製 Cache Digest 回應訊息期間消耗所有可用的 CPU 週期，從而造成拒絕服務。僅當使用具有快取摘要功能的 cache_peer 時才會發生此問題。此問題之所以存在，是因為 peer_digest.cc 中的 peerDigestHandleReply() 動態鎖定未正確處理 EOF。(CVE-2020-24606)

  - 在 Squid 4.10 之前版本中發現一個問題。由於不正確的輸入驗證，它可以非預期的方式解譯特製的 HTTP 要求，以存取早期安全性篩選器禁止的伺服器資源。
    (CVE-2020-8449)

  - 在 Squid 4.10 之前版本中發現一個問題。由於緩衝區管理不正確，遠端用戶端可造成作為反向代理伺服器的 Squid 執行個體發生緩衝區溢位。(CVE-2020-8450)

請注意，Nessus 並未測試這些問題，而是僅依據應用程式自我報告的版本號碼作出判斷。

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is     vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the     raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR     protections and may aid attackers isolating memory areas to target for remote code execution attacks.
    (CVE-2019-18679)

Note that Nessus relies on the presence of the package as reported by the vendor.

This update for squid to version 4.9 fixes the following issues :

Security issues fixed :

  - CVE-2019-13345: Fixed multiple cross-site scripting     vulnerabilities in cachemgr.cgi (bsc#1140738).

  - CVE-2019-12526: Fixed potential remote code execution     during URN processing (bsc#1156326).

  - CVE-2019-12523,CVE-2019-18676: Fixed multiple improper     validations in URI processing (bsc#1156329).

  - CVE-2019-18677: Fixed Cross-Site Request Forgery in HTTP     Request processing (bsc#1156328).

  - CVE-2019-18678: Fixed incorrect message parsing which     could have led to HTTP request splitting issue     (bsc#1156323).

  - CVE-2019-18679: Fixed information disclosure when     processing HTTP Digest Authentication (bsc#1156324).

Other issues addressed :

  - Fixed DNS failures when peer name was configured with     any upper case characters

  - Fixed several rock cache_dir corruption issues

This update was imported from the SUSE:SLE-15:Update update project.

The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2020-4743 advisory.

  - An issue was discovered in Squid before 4.10. It allows a crafted FTP server to trigger disclosure of     sensitive information from heap memory, such as information associated with other users' sessions or non-     Squid processes. (CVE-2019-12528)

  - An issue was discovered in Squid before 4.10. Due to incorrect buffer management, a remote client can     cause a buffer overflow in a Squid instance acting as a reverse proxy. (CVE-2020-8450)

  - An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A     Request Smuggling and Poisoning attack can succeed against the HTTP cache. The client sends an HTTP     request with a Content-Length header containing +\ - or an uncommon shell whitespace character prefix     to the length field-value. (CVE-2020-15049)

  - Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all     available CPU cycles during handling of a crafted Cache Digest response message. This only occurs when     cache_peer is used with the cache digests feature. The problem exists because peerDigestHandleReply()     livelocking in peer_digest.cc mishandles EOF. (CVE-2020-24606)

  - An issue was discovered in Squid before 4.10. Due to incorrect input validation, it can interpret crafted     HTTP requests in unexpected ways to access server resources prohibited by earlier security filters.
    (CVE-2020-8449)

  - An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in     ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is     parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this     buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same     structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.
    (CVE-2019-12521)

  - An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is     made. This HTTP request doesn't go through the access checks that incoming HTTP requests go through. This     causes all access checks to be bypassed and allows access to restricted HTTP servers, e.g., an attacker     can connect to HTTP servers that only listen on localhost. (CVE-2019-12523)

  - An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to     see if the request should be denied. Squid by default comes with rules to block access to the Cache     Manager, which serves detailed server information meant for the maintainer. This rule is implemented via     url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to     encode their URL to bypass the url_regex check, and gain access to the blocked resource. (CVE-2019-12524)

  - An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based     buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to     ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in     the heap. (CVE-2019-12526)

  - An issue was discovered in Squid 2.x through 2.7.STABLE9, 3.x through 3.5.28, and 4.x through 4.7. When     Squid is configured to use Basic Authentication, the Proxy-Authorization header is parsed via uudecode.
    uudecode determines how many bytes will be decoded by iterating over the input and checking its table. The     length is then used to start decoding the string. There are no checks to ensure that the length it     calculates isn't greater than the input buffer. This leads to adjacent memory being decoded as well. An     attacker would not be able to retrieve the decoded data unless the Squid maintainer had configured the     display of usernames on error pages. (CVE-2019-12529)

  - Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter     to cachemgr.cgi. (CVE-2019-18860)

  - An issue was discovered in Squid before 4.12 and 5.x before 5.0.3. Due to use of a potentially dangerous     function, Squid and the default certificate validation helper are vulnerable to a Denial of Service when     opening a TLS connection to an attacker-controlled server for HTTPS. This occurs because unrecognized     error values are mapped to NULL, but later code expects that each error value is mapped to a valid error     string. (CVE-2020-14058)

  - An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to     see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request.
    If found, it servers the request. The absolute URL can include the decoded UserInfo (username and     password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to     provide a username that has special characters to delimit the domain, and treat the rest of the URL as a     path or query string. An attacker could first make a request to their domain using an encoded username,     then when a request for the target domain comes in that decodes to the exact URL, it will serve the     attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows     an attacker to gain access to features that only reverse proxies can use, such as ESI. (CVE-2019-12520)

  - Due to incorrect string termination, Squid cachemgr.cgi 4.0 through 4.7 may access unallocated memory. On     systems with memory access protections, this can cause the CGI process to terminate unexpectedly,     resulting in a denial of service for all clients using it. (CVE-2019-12854)

  - An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a     heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity     is high due to this vulnerability occurring before normal security checks; any remote client that can     reach the proxy port can trivially perform the attack via a crafted URI scheme. (CVE-2019-18676)

  - An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because     the appended characters do not properly interact with hostname length restrictions). Due to incorrect     message processing, it can inappropriately redirect traffic to origins it should not be delivered to.
    (CVE-2019-18677)

  - An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests     through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The     resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content     at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no     effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing     whitespace between a header name and a colon. (CVE-2019-18678)

  - An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is     vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the     raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR     protections and may aid attackers isolating memory areas to target for remote code execution attacks.
    (CVE-2019-18679)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

It was found that Squid, a high-performance proxy caching server for web clients, has been affected by the following security vulnerabilities.

CVE-2019-12526

URN response handling in Squid suffers from a heap-based buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in the heap.

CVE-2019-18677

When the append_domain setting is used (because the appended characters do not properly interact with hostname length restrictions), it can inappropriately redirect traffic to origins it should not be delivered to. This happens because of incorrect message processing.

CVE-2019-18678

A programming error allows attackers to smuggle HTTP requests through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing whitespace between a header name and a colon.

CVE-2019-18679

Due to incorrect data management, Squid is vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR protections and may aid attackers isolating memory areas to target for remote code execution attacks.

For Debian 8 'Jessie', these problems have been fixed in version 3.4.8-6+deb8u9.

We recommend that you upgrade your squid3 packages.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote host is affected by the vulnerability described in GLSA-202003-34 (Squid: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in Squid. Please review       the CVE identifiers referenced below for details.
  Impact :

    A remote attacker, by sending a specially crafted request, could       possibly execute arbitrary code with the privileges of the process,       obtain sensitive information or cause a Denial of Service condition.
  Workaround :

    There is no known workaround at this time.

The remote SUSE Linux SLES11 host has a package installed that is affected by multiple vulnerabilities as referenced in the SUSE-SU-2020:14460-1 advisory.

  - An issue was discovered in Squid through 4.7. When handling the tag esi:when when ESI is enabled, Squid     calls ESIExpression::Evaluate. This function uses a fixed stack buffer to hold the expression while it's     being evaluated. When processing the expression, it could either evaluate the top of the stack, or add a     new member to the stack. When adding a new member, there is no check to ensure that the stack won't     overflow. (CVE-2019-12519)

  - An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to     see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request.
    If found, it servers the request. The absolute URL can include the decoded UserInfo (username and     password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to     provide a username that has special characters to delimit the domain, and treat the rest of the URL as a     path or query string. An attacker could first make a request to their domain using an encoded username,     then when a request for the target domain comes in that decodes to the exact URL, it will serve the     attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows     an attacker to gain access to features that only reverse proxies can use, such as ESI. (CVE-2019-12520)

  - An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in     ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is     parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this     buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same     structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.
    (CVE-2019-12521)

  - An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is     made. This HTTP request doesn't go through the access checks that incoming HTTP requests go through. This     causes all access checks to be bypassed and allows access to restricted HTTP servers, e.g., an attacker     can connect to HTTP servers that only listen on localhost. (CVE-2019-12523)

  - An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to     see if the request should be denied. Squid by default comes with rules to block access to the Cache     Manager, which serves detailed server information meant for the maintainer. This rule is implemented via     url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to     encode their URL to bypass the url_regex check, and gain access to the blocked resource. (CVE-2019-12524)

  - An issue was discovered in Squid 3.3.9 through 3.5.28 and 4.x through 4.7. When Squid is configured to use     Digest authentication, it parses the header Proxy-Authorization. It searches for certain tokens such as     domain, uri, and qop. Squid checks if this token's value starts with a quote and ends with one. If so, it     performs a memcpy of its length minus 2. Squid never checks whether the value is just a single quote     (which would satisfy its requirements), leading to a memcpy of its length minus 1. (CVE-2019-12525)

  - An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based     buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to     ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in     the heap. (CVE-2019-12526)

  - An issue was discovered in Squid before 4.10. It allows a crafted FTP server to trigger disclosure of     sensitive information from heap memory, such as information associated with other users' sessions or non-     Squid processes. (CVE-2019-12528)

  - An issue was discovered in Squid 2.x through 2.7.STABLE9, 3.x through 3.5.28, and 4.x through 4.7. When     Squid is configured to use Basic Authentication, the Proxy-Authorization header is parsed via uudecode.
    uudecode determines how many bytes will be decoded by iterating over the input and checking its table. The     length is then used to start decoding the string. There are no checks to ensure that the length it     calculates isn't greater than the input buffer. This leads to adjacent memory being decoded as well. An     attacker would not be able to retrieve the decoded data unless the Squid maintainer had configured the     display of usernames on error pages. (CVE-2019-12529)

  - The cachemgr.cgi web module of Squid through 4.7 has XSS via the user_name or auth parameter.
    (CVE-2019-13345)

  - An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a     heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity     is high due to this vulnerability occurring before normal security checks; any remote client that can     reach the proxy port can trivially perform the attack via a crafted URI scheme. (CVE-2019-18676)

  - An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because     the appended characters do not properly interact with hostname length restrictions). Due to incorrect     message processing, it can inappropriately redirect traffic to origins it should not be delivered to.
    (CVE-2019-18677)

  - An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests     through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The     resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content     at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no     effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing     whitespace between a header name and a colon. (CVE-2019-18678)

  - An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is     vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the     raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR     protections and may aid attackers isolating memory areas to target for remote code execution attacks.
    (CVE-2019-18679)

  - Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter     to cachemgr.cgi. (CVE-2019-18860)

  - An issue was discovered in Squid before 5.0.2. A remote attacker can replay a sniffed Digest     Authentication nonce to gain access to resources that are otherwise forbidden. This occurs because the     attacker can overflow the nonce reference counter (a short integer). Remote code execution may occur if     the pooled token credentials are freed (instead of replayed as valid credentials). (CVE-2020-11945)

  - An issue was discovered in Squid 5.x before 5.0.3. Due to an Incorrect Synchronization, a Denial of     Service can occur when processing objects in an SMP cache because of an Ipc::Mem::PageStack::pop ABA     problem during access to the memory page/slot management list. (CVE-2020-14059)

  - An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A     Request Smuggling and Poisoning attack can succeed against the HTTP cache. The client sends an HTTP     request with a Content-Length header containing +\ - or an uncommon shell whitespace character prefix     to the length field-value. (CVE-2020-15049)

  - An issue was discovered in Squid before 4.10. Due to incorrect input validation, it can interpret crafted     HTTP requests in unexpected ways to access server resources prohibited by earlier security filters.
    (CVE-2020-8449)

  - An issue was discovered in Squid before 4.10. Due to incorrect buffer management, a remote client can     cause a buffer overflow in a Squid instance acting as a reverse proxy. (CVE-2020-8450)

  - An issue was discovered in Squid before 4.10. Due to incorrect input validation, the NTLM authentication     credentials parser in ext_lm_group_acl may write to memory outside the credentials buffer. On systems with     memory access protections, this can result in the helper process being terminated unexpectedly. This leads     to the Squid process also terminating and a denial of service for all clients using the proxy.
    (CVE-2020-8517)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Linux/Unix 主機上安裝了一個或多個受到弱點影響的套件，且供應商未提供可用的修補程式。

  - 在 Squid 2.x、3.x 及 4.x 至 4.8 版本中發現一個問題。由於資料管理不正確，處理 HTTP 摘要式驗證時容易發生資訊洩漏。Nonce token 包含堆積記憶體配置中指標的原始位元組值。此資訊會降低 ASLR 保護，並可協助攻擊者隔離作為遠端程式碼執行攻擊目標的記憶體區域。
    (CVE-2019-18679)

請注意，Nessus 依賴供應商報告的套件存在。

據發現，Squid (適用於 Web 用戶端的高效能代理快取伺服器) 受到下列安全性弱點影響。

CVE-2019-12526

Squid 中的 URN 回應處理受到一個堆積型緩衝區溢位問題的影響。當從遠端伺服器接收資料以回應 URN 要求時，Squid 無法確保回應能夠放入緩衝區。這會導致由攻擊者控制的資料在堆積中溢位。

CVE-2019-18677

使用 append_domain 設定時 (由於附加的字元未與主機名稱長度限制正確互動)，可將流量不當重新導向至不應傳送至的來源。這是不正確的訊息處理所致。

CVE-2019-18678

存在一個程式設計錯誤，允許攻擊者透過前端軟體將 HTTP 要求走私至 Squid 執行個體，該執行個體會以不同方式分割 HTTP 要求工作流程。所產生的回應訊息會在任意 URL 上使用攻擊者控制的內容損毀 (用戶端和 Squid 之間的) 快取。僅影響攻擊者用戶端和 Squid 之間的軟體。對 Squid 本身或任何上游伺服器都沒有影響。此問題與一個要求標頭有關，該標頭的表頭名稱和冒號之間含有空格。

CVE-2019-18679

由於資料管理不正確，處理 HTTP 摘要式驗證時 Squid 容易發生資訊洩漏。Nonce token 包含堆積記憶體配置中指標的原始位元組值。此資訊會降低 ASLR 保護，並可協助攻擊者隔離作為遠端程式碼執行攻擊目標的記憶體區域。

針對 Debian 8「Jessie」，已在 3.4.8-6+deb8u9 版本中修正這些問題。

建議您升級 squid3 套件。

注意：Tenable Network Security 已直接從 DLA 安全性公告擷取前置描述區塊。Tenable 已盡量在不造成其他問題的前提下，嘗試自動清理並將其格式化。

遠端主機受到 GLSA-202003-34 中所述的弱點影響 (Squid：多個弱點) 在 Squid 中已經發現多個弱點。如需詳細資訊，請檢閱以下提及的 CVE 識別碼。影響：遠端攻擊者可傳送特製的要求，從而可能以處理程序的權限執行任意程式碼、取得敏感資訊或造成拒絕服務情況。因應措施：目前尚無已知的因應措施。

遠端 Oracle Linux 8 主機中安裝的套件受到 ELSA-2020-4743 公告中提及的多個弱點影響。

  - 在 Squid 4.10 之前版本中發現一個問題。它允許特製的 FTP 伺服器從堆積記憶體觸發敏感資訊洩漏，例如與其他使用者工作階段或非 Squid 處理程序相關的資訊。(CVE-2019-12528)

  - 在 Squid 4.10 之前版本中發現一個問題。由於緩衝區管理不正確，遠端用戶端可造成作為反向代理伺服器的 Squid 執行個體發生緩衝區溢位。(CVE-2020-8450)

  在 4.12 版之前和 5.0.3 之前 5.x 版的 Squid 中，發現 http/ContentLengthInterpreter.cc 中有一個問題。可針對 HTTP 快取發動要求走私和毒害攻擊。用戶端會傳送具有 Content-Length 標頭的 HTTP 要求，標頭中包含 + \- 或長度欄位值或含有不常見的 shell 空白字元前置詞。(CVE-2020-15049)

  - 4.13 之前和 5.0.4 之前的 5.x 版 Squid 允許一個可信節點在處理特製 Cache Digest 回應訊息期間消耗所有可用的 CPU 週期，從而造成拒絕服務。僅當使用具有快取摘要功能的 cache_peer 時才會發生此問題。此問題之所以存在，是因為 peer_digest.cc 中的 peerDigestHandleReply() 動態鎖定未正確處理 EOF。(CVE-2020-24606)

  - 在 Squid 4.10 之前版本中發現一個問題。由於不正確的輸入驗證，它可以非預期的方式解譯特製的 HTTP 要求，以存取早期安全性篩選器禁止的伺服器資源。
    (CVE-2020-8449)

  - 在 Squid 4.7 及之前版本中發現一個問題。Squid 剖析 ESI 時，會將 ESI 元素保留在 ESIContext 中。ESIContext 中有一個緩衝區，用於保留 ESIElements 堆疊。剖析新的 ESIElement 時，它會透過 addStackElement 進行新增。 addStackElement 會檢查此緩衝區中的元素數，但會差一，從而導致堆積溢位元素為 1。此溢位發生於相同結構內，因此不會影響相鄰的記憶體區塊，只會在處理時導致當機。
    (CVE-2019-12521)

  - 在 Squid 4.9 之前版本中發現一個問題。處理 URN 要求時，程式會提出對應的 HTTP 要求。此 HTTP 要求不會經過傳入 HTTP 要求所經過的存取權限檢查。這會造成所有存取權限檢查被略過，並且允許存取受限制的 HTTP 伺服器，例如，攻擊者可連線至僅在 localhost 上接聽的 HTTP 伺服器。(CVE-2019-12523)

  - 在 Squid 4.7 及之前版本中發現一個問題。處理使用者發出的要求時，Squid 會檢查其規則以查看是否應拒絕該要求。Squid 依預設使用可封鎖快取管理員存取權限的規則，而該快取管理員可爲維護者提供伺服器詳細資訊。此規則是透過 url_regex 實作。url_regex 規則 URL 的處理常式會解碼傳入的要求，這讓攻擊者可以對其 URL 進行編碼，以繞過 url_regex 檢查，並取得對封鎖資源的存取權。(CVE-2019-12524)

  - 在 Squid 4.9 之前版本中發現一個問題。Squid 中的 URN 回應處理受到一個堆積型緩衝區溢位問題的影響。當從遠端伺服器接收資料以回應 URN 要求時，Squid 無法確保回應能夠放入緩衝區。這會導致由攻擊者控制的資料在堆積中溢位。(CVE-2019-12526)

  - 在 Squid 2.x 至 2.7.STABLE9 版、3.x 至 3.5.28 和 4.x 至 4.7 版中發現一個問題。將 Squid 設定為使用基本驗證時，它會透過 uudecode 剖析 Proxy-Authorization 標頭。
    uudecode 透過反覆輸入並檢查其表格來決定將要解碼的位元組數量，然後使用該長度開始解碼字串。沒有任何檢查確保其計算的長度不會大於輸入緩衝區。這也會導致相鄰記憶體被解碼。除非 Squid 維護者已設定錯誤頁面上的使用者名稱顯示，否則攻擊者無法擷取解碼後的資料。(CVE-2019-12529)

  - 使用特定的網頁瀏覽器時，Squid 4.9 之前版本會將 host (即主機名稱) 參數中的 HTML 錯誤處理為 cachemgr.cgi。(CVE-2019-18860)

  在 4.12 版之前和 5.0.3 之前 5.x 版的 Squid 中，發現一個問題。由於使用了可能危險的函式，Squid 和預設的憑證驗證協助程式在為 HTTPS 開啓連線至受攻擊者控制之伺服器的 TLS 連線時，容易遭受拒絕服務攻擊。這是因為無法識別的錯誤值會對應至 NULL，而之後的程式碼預期每個錯誤值對應至有效的錯誤字串。(CVE-2020-14058)

  - 在 Squid 4.7 以及之前的所有版本和第 5 版中發現一個問題。Squid 會在接收要求時檢查其快取，以確認是否可以提供回應。它透過對要求的絕對 URL 進行 MD5 雜湊來實現這一點。
    如果找到，則爲要求提供服務。絕對 URL 可包含針對特定通訊協定解碼後的 UserInfo (使用者名稱和密碼)，此解碼後的資訊會附加在網域之前。攻擊者可藉此提供具有特殊字元的使用者名稱來分隔網域，並將 URL 的其餘部分視為路徑或查詢字串。攻擊者可先使用編碼的使用者名稱向其網域提出要求，然後當解碼為確切 URL 的目標網域要求傳入時，程式會提供攻擊者的 HTML，而非真正的 HTML。若 Squid 伺服器也充當反向 Proxy，這會允許攻擊者存取只有反向 Proxy 可以使用的功能，例如 ESI。(CVE-2019-12520)

  - 由於字串結尾錯誤，Squid cachemgr.cgi 4.0 至 4.7 可能會存取未配置的記憶體。在具有記憶體存取保護機制的系統上，這可造成 CGI 處理程序意外終止，進而導致所有使用該處理程序的用戶端拒絕服務。(CVE-2019-12854)

  - 在 Squid 3.x、4.x 至 4.8 版本中發現一個問題。由於輸入驗證不正確，程式會發生堆積型緩衝區溢位，從而導致使用 Proxy 的所有用戶端拒絕服務。此弱點發生在正常安全性檢查之前，因此屬於高嚴重性問題。任何可連線至 Proxy 連接埠的遠端用戶端皆可透過特製的 URI 配置輕鬆執行攻擊。(CVE-2019-18676)

  - 使用 append_domain 設定時，Squid 3.x 以及 4.x 至 4.8 版中會產生問題 (因為附加字元未與主機名稱長度限制正確互動)。由於訊息處理不正確，它可以錯誤地將流量重新導向至不應傳送的目的地來源。
    (CVE-2019-18677)

  - 在 Squid 3.x、4.x 至 4.8 版本中發現一個問題。它允許攻擊者透過前端軟體將 HTTP 要求走私至 Squid 執行個體，然後由該執行個體以不同方式分割 HTTP 要求工作流程。所產生的回應訊息會在任意 URL 上使用攻擊者控制的內容損毀 (用戶端和 Squid 之間的) 快取。僅影響攻擊者用戶端和 Squid 之間的軟體。對 Squid 本身或任何上游伺服器都沒有影響。此問題涉及標頭名稱和冒號之間含有空格的一個要求標頭。(CVE-2019-18678)

  - 在 Squid 2.x、3.x 及 4.x 至 4.8 版本中發現一個問題。由於資料管理不正確，處理 HTTP 摘要式驗證時容易發生資訊洩漏。Nonce token 包含堆積記憶體配置中指標的原始位元組值。此資訊會降低 ASLR 保護，並可協助攻擊者隔離作為遠端程式碼執行攻擊目標的記憶體區域。
    (CVE-2019-18679)

請注意，Nessus 並未測試這些問題，而是僅依據應用程式自我報告的版本號碼作出判斷。

ID	名称	产品	系列	发布时间	最近更新时间	严重程度
145969	CentOS 8 : Squid：4（CESA-2020：4743)	Nessus	CentOS Local Security Checks	2021/2/1	2023/2/8	critical
131707	Fedora 30：7:squid (2019-0b16cbdd0e)	Nessus	Fedora Local Security Checks	2019/12/5	2019/12/17	critical
131714	Fedora 31 : 7:squid (2019-9538783033)	Nessus	Fedora Local Security Checks	2019/12/5	2019/12/17	critical
145969	CentOS 8：squid: 4 (CESA-2020: 4743)	Nessus	CentOS Local Security Checks	2021/2/1	2023/2/8	critical
140199	Amazon Linux 2：squid (ALAS-2020-1486)	Nessus	Amazon Linux Local Security Checks	2020/9/2	2024/12/11	high
136430	Debian DSA-4682-1：squid - 安全性更新	Nessus	Debian Local Security Checks	2020/5/11	2024/3/13	critical
142412	RHEL 8：Squid：4 (RHSA-2020：4743)	Nessus	Red Hat Local Security Checks	2020/11/4	2024/11/7	critical
184691	Rocky Linux 8squid:4 (RLSA-2020:4743)	Nessus	Rocky Linux Local Security Checks	2023/11/6	2023/11/6	critical
222807	Linux Distros Unpatched Vulnerability : CVE-2019-18679	Nessus	Misc.	2025/3/4	2025/8/20	high
131219	openSUSE Security Update : squid (openSUSE-2019-2540)	Nessus	SuSE Local Security Checks	2019/11/22	2024/4/10	critical
131220	openSUSE Security Update : squid (openSUSE-2019-2541)	Nessus	SuSE Local Security Checks	2019/11/22	2024/4/10	critical
180917	Oracle Linux 8 : squid:4 (ELSA-2020-4743)	Nessus	Oracle Linux Local Security Checks	2023/9/7	2023/9/7	critical
131961	Debian DLA-2028-1 : squid3 security update	Nessus	Debian Local Security Checks	2019/12/12	2021/1/11	critical
134640	GLSA-202003-34 : Squid: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	2020/3/18	2024/3/21	critical
150657	SUSE SLES11 Security Update : squid3 (SUSE-SU-2020:14460-1)	Nessus	SuSE Local Security Checks	2021/6/10	2023/12/26	critical
222807	Linux Distros 未修補弱點：CVE-2019-18679	Nessus	Misc.	2025/3/4	2025/8/20	high
131961	Debian DLA-2028-1：squid3 安全性更新	Nessus	Debian Local Security Checks	2019/12/12	2021/1/11	critical
134640	GLSA-202003-34：Squid：多個弱點	Nessus	Gentoo Local Security Checks	2020/3/18	2024/3/21	critical
180917	Oracle Linux 8：squid：4 (ELSA-2020-4743)	Nessus	Oracle Linux Local Security Checks	2023/9/7	2023/9/7	critical

检测

插件搜索

critical

critical

critical

critical

high

critical

critical

critical

high

critical

critical

critical

critical

critical

critical

high

critical

critical

critical