The CentOS Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare CENTOS-STREAM8:CLSA-2026:1791261872 advisory.

  - Certain DNSSEC aspects of the DNS protocol (in RFC 4033, 4034, 4035, 6840, and related RFCs) allow remote     attackers to cause a denial of service (CPU consumption) via one or more DNSSEC responses, aka the     KeyTrap issue. One of the concerns is that, when there is a zone with many DNSKEY and RRSIG records, the     protocol specification implies that an algorithm must evaluate all combinations of DNSKEY and RRSIG     records. (CVE-2023-50387)

  - In NLnetLabs Unbound up to and including 1.26.0, a degradation of service vulnerability is present in the     TCP/DoT reading procedure where there is no limit on consecutive reads. A malicious actor that can stream     and sustain a rate of distinct uncached names over the TCP/DoT connection, monopolizes a single worker's     entire event loop for as long as its writes stay ahead of the drain. (CVE-2026-80225)

  - In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can     lead to a heap buffer overflow during the RRSet canonicalisation routine. This is caused by missing to add     the first owner name into the buffer length check. A malicious actor operating a malicious name server or     tampering with an incoming response to Unbound (canonicalisation happens before DNSSEC validation), can     trigger the vulnerability. (CVE-2026-81634)

  - Novel vulnerabilities to launch algorithmic complexity attacks on DNSSEC have been researched under the     term 'ReTrap'. These result in degradation of service when malicious zones are used to serve the     algorithmic complexity vulnerabilities. NLnet Labs Unbound up to and including 1.26.0 is vulnerable to     some of them. TagTrap, where the triple(Zone, Algo, KeyTag) matching mechanism introduces a significant     attack vector when resolvers handle malicious responses containing numerous mismatched DNSKEY, RRSIG, and     DS record. DelegationTrap, where constructing the chain-of-trust requires iterative validation of DNSKEY     and DS records from the root zone downward. For deeply nested domains, this results in significant     computational overhead. NsecTrap, where responses with excessive invalid NSEC records compel the resolver     to validate each one. AdditionalTrap, where Unbound by default would try to DNSSEC validate the ADDITIONAL     section as well. This can be exploited to waste validation resources by malicious users. (CVE-2026-85501)

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

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-3127 advisory.

    In NLnet Labs Unbound 1.13.2 up to and including 1.26.1, a vulnerability in ZONEMD configured zones     (zonemd-check: yes) which are located below (but not at) a trust anchor allow for an attack window where     (tampered with) zone contents are served (or stored to disk) prior to the ZONEMD integrity check. This is     caused by the needed DS/DNSKEY asynchronous resolution that needs to happen before the ZONEMD check     completes. If a zonefile is written to disk (zonefile: option) while the ZONEMD check failed, the tampered     data are reloaded on startup and available until ZONEMD verification concludes again. If verification     fails, the data is not served any more but still persists on disk for future reloads. (CVE-2026-77955)

    In NLnetLabs Unbound up to and including 1.26.0, a degradation of service vulnerability is present in the     TCP/DoT reading procedure where there is no limit on consecutive reads. A malicious actor that can stream     and sustain a rate of distinct uncached names over the TCP/DoT connection, monopolizes a single worker's     entire event loop for as long as its writes stay ahead of the drain. (CVE-2026-80225)

    In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can     lead to a heap buffer overflow during the RRSet canonicalisation routine. This is caused by missing to add     the first owner name into the buffer length check. A malicious actor operating a malicious name server or     tampering with an incoming response to Unbound (canonicalisation happens before DNSSEC validation), can     trigger the vulnerability. (CVE-2026-81634)

    In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in that can progressively     corrupt heap memory and under certain systems and compilation options could lead to remote code execution.
    The vulnerability starts when CNAME synthesis during an upstream response needs to enforce(rewrite) a max     TTL value in the packet buffer. Coupled with a compression pointer that points to the overwritten value     and invalidates the domain name, it leads to an error path that does not properly move the buffer position     and allows for the heap buffer overflow. Since this is heavily reliant on heap memory layout, results are     memory corruption that eventually leads to a crash and under specific systems and compilation options     remote code execution. (CVE-2026-82717)

    NLnet Labs Unbound 1.12.0 up to and including 1.26.0 has a use-after-free vulnerability when compiled for     DNS-over-HTTPs support with '--with-libnghttp2'. During failure code paths (i.e., RPZ drop query, jostle     due to heavy traffic), a dropped DoH stream brings down the whole DoH session and does not account     properly for other DoH streams in the same session. This leads to use-after-free in those code paths. If     the prerequisites are satisfied (possible RPZ drop or heavy client traffic), a malicious actor can trigger     the vulnerability with a single DoH connection and the appropriate traffic. Impact is limited as the reads     are not user controlled and the use-after-free leads to early returns. However, a hardened allocator can     catch the use-after-free and controllably terminate the process resulting to denial of service.
    (CVE-2026-82720)

    Novel vulnerabilities to launch algorithmic complexity attacks on DNSSEC have been researched under the     term 'ReTrap'. These result in degradation of service when malicious zones are used to serve the     algorithmic complexity vulnerabilities. NLnet Labs Unbound up to and including 1.26.0 is vulnerable to     some of them. TagTrap, where  the triple(Zone, Algo, KeyTag) matching mechanism introduces a significant     attack vector when resolvers handle malicious responses containing numerous mismatched DNSKEY, RRSIG, and     DS record. DelegationTrap, where constructing the chain-of-trust requires iterative validation of DNSKEY     and DS records from the root zone downward. For deeply nested domains, this results in significant     computational overhead. NsecTrap, where  responses with excessive invalid NSEC records compel the resolver     to validate each one. AdditionalTrap, where Unbound by default would try to DNSSEC validate the ADDITIONAL     section as well. This can be exploited to waste validation resources by malicious users. (CVE-2026-85501)

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

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

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:4624-1 advisory.

    - CVE-2026-77860: 'serve-expired' can bypass Unbound 'wait-limit' (bsc#1280403).
    - CVE-2026-77955: Possible ZONEMD verification bypass window (bsc#1280404).
    - CVE-2026-78227: Use-after-free in DoQ stream output buffer on reset re-transmission (bsc#1280405).
    - CVE-2026-80225: Possible degradation of service from continuous queries on the same TCP/DoT connection     (bsc#1280406).
    - CVE-2026-81634: Possible heap buffer overflow during DNSSEC canonicalization (bsc#1280409).
    - CVE-2026-81642: Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY     (bsc#1280411).
    - CVE-2026-82717: CNAME synthesis could lead to heap corruption (bsc#1280412).
    - CVE-2026-82720: Use-after-free in DoH stream cleanup code path (bsc#1280413).
    - CVE-2026-85501: Retrap: Novel Vulnerabilities to launch Algorithmic Complexity Attacks on DNSSEC     (bsc#1280414).

    Changes for libunbound-devel-mini:

    - Updated to version 1.26.1

    Changes for unbound:

    - Updated to version 1.26.1

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

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

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

  - In NLnetLabs Unbound up to and including 1.26.0, a degradation of service vulnerability is present in the     TCP/DoT reading procedure where there is no limit on consecutive reads. A malicious actor that can stream     and sustain a rate of distinct uncached names over the TCP/DoT connection, monopolizes a single worker's     entire event loop for as long as its writes stay ahead of the drain. (CVE-2026-80225)

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
363115	CentOS Linux 8 [TuxCare] Security Update: python3-unbound / unbound / unbound-devel / unbound-libs Multiple Vulnerabilities (CENTOS-STREAM8:CLSA-2026:1791261872)	Nessus	CentOS Local Security Checks	2026/10/6	2026/10/19	high
351052	Amazon Linux 2023 : python3-unbound, unbound, unbound-anchor (ALAS2023-2026-3127)	Nessus	Amazon Linux Local Security Checks	2026/9/29	2026/10/2	critical
365323	SUSE SLES15 Security Update : unbound (SUSE-SU-2026:4624-1)	Nessus	SuSE Local Security Checks	2026/10/13	2026/10/13	critical
346398	Linux Distros Unpatched Vulnerability : CVE-2026-80225	Nessus	Misc.	2026/9/16	2026/11/10	high

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