Updated kdenetwork packages that fix three security issues are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

The kdenetwork packages contain networking applications for the K Desktop Environment (KDE). Krfb Desktop Sharing, which is a part of the kdenetwork package, is a server application that allows session sharing between users. Krfb uses the LibVNCServer library.

A NULL pointer dereference flaw was found in the way LibVNCServer handled certain ClientCutText message. A remote attacker could use this flaw to crash the VNC server by sending a specially crafted ClientCutText message from a VNC client. (CVE-2014-6053)

A divide-by-zero flaw was found in the way LibVNCServer handled the scaling factor when it was set to '0'. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6054)

Two stack-based buffer overflow flaws were found in the way LibVNCServer handled file transfers. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6055)

Red Hat would like to thank oCERT for reporting these issues. oCERT acknowledges Nicolas Ruff as the original reporter.

Note: Prior to this update, the kdenetwork packages used an embedded copy of the LibVNCServer library. With this update, the kdenetwork packages have been modified to use the system LibVNCServer packages.
Therefore, the update provided by RHSA-2014:1826 must be installed to fully address the issues in krfb described above.

All kdenetwork users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. All running instances of the krfb server must be restarted for this update to take effect.

Updated libvncserver packages fix security vulnerabilities :

A malicious VNC server can trigger incorrect memory management handling by advertising a large screen size parameter to the VNC client. This would result in multiple memory corruptions and could allow remote code execution on the VNC client (CVE-2014-6051, CVE-2014-6052).

A malicious VNC client can trigger multiple DoS conditions on the VNC server by advertising a large screen size, ClientCutText message length and/or a zero scaling factor parameter (CVE-2014-6053, CVE-2014-6054).

A malicious VNC client can trigger multiple stack-based buffer overflows by passing a long file and directory names and/or attributes (FileTime) when using the file transfer message feature (CVE-2014-6055).

Additionally libvncserver has been built against the new system minilzo library which is also being provided with this advisory.

The LibVNCServer package was updated to fix the following security issues :

  - bsc#897031: fix several security issues :

  - CVE-2014-6051: Integer overflow in MallocFrameBuffer()     on client side.

  - CVE-2014-6052: Lack of malloc() return value checking on     client side.

  - CVE-2014-6053: Server crash on a very large     ClientCutText message.

  - CVE-2014-6054: Server crash when scaling factor is set     to zero.

  - CVE-2014-6055: Multiple stack overflows in File Transfer     feature.

  - bsc#854151: Restrict the SSL cipher suite.

The remote Ubuntu 14.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-2365-1 advisory.

    Nicolas Ruff discovered that LibVNCServer incorrectly handled memory when being advertised large screen     sizes by the server. If a user were tricked into connecting to a malicious server, an attacker could use     this issue to cause a denial of service, or possibly execute arbitrary code. (CVE-2014-6051,     CVE-2014-6052)

    Nicolas Ruff discovered that LibVNCServer incorrectly handled large ClientCutText messages. A remote     attacker could use this issue to cause a server to crash, resulting in a denial of service.
    (CVE-2014-6053)

    Nicolas Ruff discovered that LibVNCServer incorrectly handled zero scaling factor values. A remote     attacker could use this issue to cause a server to crash, resulting in a denial of service.
    (CVE-2014-6054)

    Nicolas Ruff discovered that LibVNCServer incorrectly handled memory in the file transfer feature. A     remote attacker could use this issue to cause a server to crash, resulting in a denial of service, or     possibly execute arbitrary code. (CVE-2014-6055)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

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

Various security fixes, including CVE-2014-6051, CVE-2014-6052, CVE-2014-6053, CVE-2014-6054, CVE-2014-6055

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

An integer overflow flaw, leading to a heap-based buffer overflow, was found in the way screen sizes were handled by LibVNCServer. A malicious VNC server could use this flaw to cause a client to crash or, potentially, execute arbitrary code in the client. (CVE-2014-6051)

A NULL pointer dereference flaw was found in LibVNCServer's framebuffer setup. A malicious VNC server could use this flaw to cause a VNC client to crash. (CVE-2014-6052)

A NULL pointer dereference flaw was found in the way LibVNCServer handled certain ClientCutText message. A remote attacker could use this flaw to crash the VNC server by sending a specially crafted ClientCutText message from a VNC client. (CVE-2014-6053)

A divide-by-zero flaw was found in the way LibVNCServer handled the scaling factor when it was set to '0'. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6054)

Two stack-based buffer overflow flaws were found in the way LibVNCServer handled file transfers. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6055)

All running applications linked against libvncserver must be restarted for this update to take effect.

Several vulnerabilities have been discovered in libvncserver, a library to implement VNC server functionality. These vulnerabilities might result in the execution of arbitrary code or denial of service in both the client and the server side.

Several vulnerabilities have recently been discovered in TightVNC 1.x, an X11 based VNC server/viewer application for Windows and Unix.

CVE-2014-6053

The rfbProcessClientNormalMessage function in rfbserver.c in TightVNC server did not properly handle attempts to send a large amount of ClientCutText data, which allowed remote attackers to cause a denial of service (memory consumption or daemon crash) via a crafted message that was processed by using a single unchecked malloc.

CVE-2018-7225

rfbProcessClientNormalMessage() in rfbserver.c did not sanitize msg.cct.length, leading to access to uninitialized and potentially sensitive data or possibly unspecified other impact (e.g., an integer overflow) via specially crafted VNC packets.

CVE-2019-8287

TightVNC code contained global buffer overflow in HandleCoRREBBP macro function, which could potentially have result in code execution. This attack appeared to be exploitable via network connectivity.

(aka CVE-2018-20020/libvncserver)

CVE-2018-20021

TightVNC in vncviewer/rfbproto.c contained a CWE-835: Infinite loop vulnerability. The vulnerability allowed an attacker to consume an excessive amount of resources like CPU and RAM.

CVE-2018-20022

TightVNC's vncviewer contained multiple weaknesses CWE-665: Improper Initialization vulnerability in VNC client code that allowed attackers to read stack memory and could be abused for information disclosure.
Combined with another vulnerability, it could be used to leak stack memory layout and in bypassing ASLR.

CVE-2019-15678

TightVNC code version contained heap buffer overflow in rfbServerCutText handler, which could have potentially resulted in code execution. This attack appeared to be exploitable via network connectivity.

(partially aka CVE-2018-20748/libvnvserver)

CVE-2019-15679

TightVNC's vncviewer code contained a heap buffer overflow in InitialiseRFBConnection function, which could have potentially resulted in code execution. This attack appeared to be exploitable via network connectivity.

(partially aka CVE-2018-20748/libvnvserver)

CVE-2019-15680

TightVNC's vncviewer code contained a NULL pointer dereference in HandleZlibBPP function, which could have resulted in Denial of System (DoS). This attack appeared to be exploitable via network connectivity.

CVE-2019-15681

TightVNC contained a memory leak (CWE-655) in VNC server code, which allowed an attacker to read stack memory and could have been abused for information disclosure. Combined with another vulnerability, it could have been used to leak stack memory and bypass ASLR. This attack appeared to be exploitable via network connectivity.

For Debian 8 'Jessie', these problems have been fixed in version 1.3.9-6.5+deb8u1.

We recommend that you upgrade your tightvnc 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 Oracle Linux 6 / 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2014-1826 advisory.

    - Fix CVE-2014-6051 (integer overflow in screen size handling) (bug #1157668)
    - Fix CVE-2014-6052 (NULL pointer dereference in framebuffer setup)       (bug #1157668)
    - Fix CVE-2014-6053 (NULL pointer dereference in ClientCutText message       handling) (bug #1157668)
    - Fix CVE-2014-6054 (server divide-by-zero in scaling factor handling)       (bug #1157668)
    - Fix CVE-2014-6055 (server stacked-based buffer overflow in file transfer       handling) (bug #1157668)
    - Revert CVE-2011-0904 and CVE-2011-0905 patch because libvncserver is not       vulnerable (bug #696767)
    - Fix CVE-2011-0904 and CVE-2011-0905 in more generic way (bug #696767)
    - Fix CVE-2011-0904 (bug #696767)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

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

Updated libvncserver packages fix security vulnerabilities :

An integer overflow in liblzo before 2.07 allows attackers to cause a denial of service or possibly code execution in applications using performing LZO decompression on a compressed payload from the attacker (CVE-2014-4607).

The libvncserver library is built with a bundled copy of minilzo, which is a part of liblzo containing the vulnerable code.

A malicious VNC server can trigger incorrect memory management handling by advertising a large screen size parameter to the VNC client. This would result in multiple memory corruptions and could allow remote code execution on the VNC client (CVE-2014-6051, CVE-2014-6052).

A malicious VNC client can trigger multiple DoS conditions on the VNC server by advertising a large screen size, ClientCutText message length and/or a zero scaling factor parameter (CVE-2014-6053, CVE-2014-6054).

A malicious VNC client can trigger multiple stack-based buffer overflows by passing a long file and directory names and/or attributes (FileTime) when using the file transfer message feature (CVE-2014-6055).

The LibVNCServer package was updated to fix the following security issues :

  - bsc#897031: fix several security issues :

  - CVE-2014-6051: Integer overflow in MallocFrameBuffer()     on client side.

  - CVE-2014-6052: Lack of malloc() return value checking on     client side.

  - CVE-2014-6053: Server crash on a very large     ClientCutText message.

  - CVE-2014-6054: Server crash when scaling factor is set     to zero.

  - CVE-2014-6055: Multiple stack overflows in File Transfer     feature.

  - bsc#854151: Restrict the SSL cipher suite.

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

The libvncserver package was updated to fix the following security issues :

  - bsc#897031: fix several security issues :

  - CVE-2014-6051: Integer overflow in MallocFrameBuffer()     on client side.

  - CVE-2014-6052: Lack of malloc() return value checking on     client side.

  - CVE-2014-6053: Server crash on a very large     ClientCutText message.

  - CVE-2014-6054: Server crash when scaling factor is set     to zero.

  - CVE-2014-6055: Multiple stack overflows in File Transfer     feature.

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

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

  - The rfbProcessClientNormalMessage function in libvncserver/rfbserver.c in LibVNCServer 0.9.9 and earlier     does not properly handle attempts to send a large amount of ClientCutText data, which allows remote     attackers to cause a denial of service (memory consumption or daemon crash) via a crafted message that is     processed by using a single unchecked malloc. (CVE-2014-6053)

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

ID	名称	产品	系列	发布时间	最近更新时间	严重程度
79203	RHEL 7 : kdenetwork (RHSA-2014:1827)	Nessus	Red Hat Local Security Checks	2014/11/12	2021/1/14	medium
79219	CentOS 7 : kdenetwork (CESA-2014:1827)	Nessus	CentOS Local Security Checks	2014/11/13	2021/1/4	medium
79589	Mandriva Linux Security Advisory : libvncserver (MDVSA-2014:229)	Nessus	Mandriva Local Security Checks	2014/11/27	2021/1/6	high
87389	openSUSE Security Update : LibVNCServer (openSUSE-2015-851)	Nessus	SuSE Local Security Checks	2015/12/16	2021/1/19	high
77982	Ubuntu 14.04 LTS : LibVNCServer vulnerabilities (USN-2365-1)	Nessus	Ubuntu Local Security Checks	2014/9/30	2024/8/27	critical
78000	Fedora 21 : libvncserver-0.9.10-0.6.20140718git9453be42.fc21 (2014-11685)	Nessus	Fedora Local Security Checks	2014/10/1	2021/1/11	high
79230	Scientific Linux Security Update : libvncserver on SL6.x, SL7.x i386/x86_64 (20141111)	Nessus	Scientific Linux Local Security Checks	2014/11/13	2021/1/14	high
79629	Debian DSA-3081-1 : libvncserver - security update	Nessus	Debian Local Security Checks	2014/12/1	2021/1/11	high
132345	Debian DLA-2045-1 : tightvnc security update	Nessus	Debian Local Security Checks	2019/12/23	2024/4/2	critical
79199	Oracle Linux 6 / 7 : libvncserver (ELSA-2014-1826)	Nessus	Oracle Linux Local Security Checks	2014/11/12	2025/4/29	high
82399	Mandriva Linux Security Advisory : libvncserver (MDVSA-2015:146)	Nessus	Mandriva Local Security Checks	2015/3/30	2021/1/14	high
87064	SUSE SLED12 / SLES12 Security Update : LibVNCServer (SUSE-SU-2015:2088-1)	Nessus	SuSE Local Security Checks	2015/11/25	2021/1/6	high
87105	SUSE SLED11 / SLES11 Security Update : LibVNCServer (SUSE-SU-2015:2110-1)	Nessus	SuSE Local Security Checks	2015/11/30	2021/1/6	high
218229	Linux Distros Unpatched Vulnerability : CVE-2014-6053	Nessus	Misc.	2025/3/4	2026/5/30	high

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