c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7.

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8951-1 advisory.

    It was discovered that c-ares incorrectly parsed certain SOA replies. A remote attacker could possibly use     this issue to cause c-ares to crash, resulting in a denial of service. This issue only affected Ubuntu     16.04 LTS and Ubuntu 18.04 LTS. (CVE-2020-22217)

    It was discovered that c-ares incorrectly handled certain sortlist strings. A remote attacker could     possibly use this issue to cause c-ares to crash, resulting in a denial of service, or execute arbitrary     code. This issue only affected Ubuntu 16.04 LTS. (CVE-2022-4904)

    It was discovered that c-ares did not properly limit DNS compression pointer hops or assembled name     lengths when parsing DNS names. A remote attacker could possibly use this issue to cause c-ares to use     excessive resources, resulting in a denial of service. (CVE-2026-69184)

    It was discovered that c-ares did not properly validate record count fields before allocating memory when     parsing DNS responses. A remote attacker could possibly use this issue to cause c-ares to use excessive     resources, resulting in a denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04     LTS. (CVE-2026-69186)

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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-
    controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough
    bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question
    validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to
    reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and
    release cycles that can degrade or deny name resolution, without causing memory corruption or information
    disclosure. This issue is fixed in version 1.34.7. (CVE-2026-69186)

The remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:4021-1 advisory.

    - CVE-2024-25629: out of bounds read in ares__read_line() (bsc#1220279).
    - CVE-2025-31498: use-after-free in read_answers() when process_answer() may re-enqueue a query     (bsc#1240955).
    - CVE-2025-62408: c-ares 1.32.3-1.34.5 use after free() (bsc#1254738).
    - CVE-2026-33630: Use-after-free / double-free in c-ares query-completion handling, remotely triggerable     via       ares_getaddrinfo() over TCP (bsc#1270416).
    - CVE-2026-69184: CPU-exhaustion denial of service via unbounded DNS name compression pointer chains     (bsc#1276290).
    - CVE-2026-69186: Memory-amplification denial of service via unvalidated DNS header record counts     (bsc#1276291).

    Changes for c-ares:

    - updated to 1.36.8.

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 remote openSUSE 16 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:21721-1 advisory.

    Updat to c-ares 1.36.8.

    - CVE-2026-33630: remotely triggerable use-after-free/double-free in query-completion handling via     `ares_getaddrinfo()`       over TCP (bsc#1270416).
    - CVE-2026-69184: CPU exhaustion denial of service via unbounded DNS name compression pointer chains     (bsc#1276290).
    - CVE-2026-69186: memory amplification denial of service via unvalidated DNS header record counts     (bsc#1276291).

    Changes for c-ares:

    - For details, see https://c-ares.org/changelog.html.

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.

  - c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-     controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough     bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question     validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to     reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and     release cycles that can degrade or deny name resolution, without causing memory corruption or information     disclosure. This issue is fixed in version 1.34.7. (CVE-2026-69186)

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

ID	Name	Product	Family	Type	Severity
370512	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : c-ares vulnerabilities (USN-8951-1)	Nessus	Ubuntu Local Security Checks	Local	high
476257	Echo: c-ares-1.29.0: security update to 1.29.0+e1c-ares-1.34.6: security update to 1.34.6+e1	Tenable Cloud Security	Echo Local Security Checks	Local	medium
476257	Echo: c-ares-1.29.0: security update to 1.29.0+e1c-ares-1.34.6: security update to 1.34.6+e1	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	medium
348453	SUSE SLED15 / SLES15 Security Update : c-ares (SUSE-SU-2026:4021-1)	Nessus	SuSE Local Security Checks	Local	high
342573	openSUSE 16 Security Update : c-ares (openSUSE-SU-2026:21721-1)	Nessus	SuSE Local Security Checks	Local	high
334407	Linux Distros Unpatched Vulnerability : CVE-2026-69186	Nessus	Misc.	Local	medium

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