c-ares is an asynchronous resolver library. From ver 1.32.3 until 1.34.7, a use-after-free / double-free in c-ares' query-completion handling. The same flaw — a query's callback being invoked while the query is still linked in the channel's internal lookup structures — is present at multiple points in the resend/finish path (timeout handling, response handling, and query dispatch). If the query, or for ares_getaddrinfo() the owning host_query, is freed as a side effect of that callback, it is then accessed and/or freed a second time. This vulnerability is fixed in ver 1.34.7.

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

  - c-ares is an asynchronous resolver library. From ver 1.32.3 until 1.34.7, a use-after-free / double-free
    in c-ares' query-completion handling. The same flaw — a query's callback being invoked while the query is
    still linked in the channel's internal lookup structures — is present at multiple points in the
    resend/finish path (timeout handling, response handling, and query dispatch). If the query, or for
    ares_getaddrinfo() the owning host_query, is freed as a side effect of that callback, it is then accessed
    and/or freed a second time. This vulnerability is fixed in ver 1.34.7. (CVE-2026-33630)

The Rocky Linux 10.2 host has packages installed that are affected by a vulnerability as referenced in the CIQ crlsa-2026_42096 advisory.

    * c-ares: c-ares: Use-after-free / double-free in query-completion handling (CVE-2026-33630)

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

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

The remote Ubuntu 26.04 LTS host has packages installed that are affected by a vulnerability as referenced in the USN-8844-1 advisory.

    It was discovered that c-ares incorrectly handled certain query completion callbacks. An attacker could     possibly use this issue to trigger a use- after-free or double-free, resulting in a denial of service or     arbitrary code execution.

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

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

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 version of Tencent Linux installed on the remote TencentOS Server 4 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0665 advisory.

    Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

    CVE-2026-33630:
    A flaw was found in c-ares. A use-after-free / double-free vulnerability exists in the query-completion     handling path, where a query callback is invoked while the query is still linked in internal lookup     structures. A remote attacker can exploit this via ares_getaddrinfo() over TCP by sending crafted DNS     responses that force an EDNS-downgrade retry followed by a connection reset, causing the internal     completion handler to access freed memory. This leads to memory corruption and a crash (denial of     service), with potential for further impact depending on the allocator and build configuration.

    CVE-2026-12151:
    Impact:
    The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message     but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many     small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively     causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of     service.

    Affected applications are those using the undici WebSocket client (new WebSocket(...)) or the     WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket     endpoint.

    All releases starting at undici 6.17.0 are affected.

    Patches:Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0.Workarounds:
    No workaround is available. The fix must be applied through an upgrade.

Tenable has extracted the preceding description block directly from the Tencent 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.

The remote Oracle Linux 10 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2026-42096 advisory.

    [1.34.6-2]
    - Fix double-free in process_timeouts() (CVE-2026-33630)       Resolves: RHEL-192867

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

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

The remote RockyLinux 10 host has packages installed that are affected by a vulnerability as referenced in the RLSA-2026:42096 advisory.

    * c-ares: c-ares: Use-after-free / double-free in query-completion handling (CVE-2026-33630)

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

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

The remote AlmaLinux 10 host has packages installed that are affected by a vulnerability as referenced in the ALSA-2026:42096 advisory.

    * c-ares: c-ares: Use-after-free / double-free in query-completion handling (CVE-2026-33630)

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

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

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1980 advisory.

    A use-after-free / double-free in c-ares' query-completion handling. Thesame flaw -- a query's callback     being invoked while the query is stilllinked in the channel's internal lookup structures -- is present     atmultiple points in the resend/finish path (timeout handling, responsehandling, and query dispatch). If     the query, or for `ares_getaddrinfo()`the owning `host_query`, is freed as a side effect of that callback,     itis then accessed and/or freed a second time. (CVE-2026-33630)

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

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

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1981 advisory.

    A use-after-free / double-free in c-ares' query-completion handling. Thesame flaw -- a query's callback     being invoked while the query is stilllinked in the channel's internal lookup structures -- is present     atmultiple points in the resend/finish path (timeout handling, responsehandling, and query dispatch). If     the query, or for `ares_getaddrinfo()`the owning `host_query`, is freed as a side effect of that callback,     itis then accessed and/or freed a second time. (CVE-2026-33630)

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

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

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-d70d93fcd7 advisory.

    1.34.7 accidentally broke the API compatibility, this is fixed in 1.34.8.

    ----

    - update to 1.34.7
    - fixes CVE-2026-33630 (GHSA-6wfj-rwm7-3542) and GHSA-pjmc-gx33-gc76 and GHSA-jv8r-gqr9-68wj

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

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

The remote Redhat Enterprise Linux 10 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2026:42096 advisory.

    The c-ares C library defines asynchronous DNS (Domain Name System) requests and provides name resolving     API.

    Security Fix(es):

    * c-ares: c-ares: Use-after-free / double-free in query-completion handling (CVE-2026-33630)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-950a662010 advisory.

    - update to 1.34.7
    - fixes CVE-2026-33630 (GHSA-6wfj-rwm7-3542) and GHSA-pjmc-gx33-gc76 and GHSA-jv8r-gqr9-68wj

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

Note that Nessus has not tested for this issue 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. From ver 1.32.3 until 1.34.7, a use-after-free / double-free     in c-ares' query-completion handling. The same flaw  a query's callback being invoked while the query is     still linked in the channel's internal lookup structures  is present at multiple points in the     resend/finish path (timeout handling, response handling, and query dispatch). If the query, or for     ares_getaddrinfo() the owning host_query, is freed as a side effect of that callback, it is then accessed     and/or freed a second time. This vulnerability is fixed in ver 1.34.7. (CVE-2026-33630)

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

The version of c-ares installed on the remote host is prior to 1.34.7. It is, therefore, affected by a vulnerability as referenced in the SSA:2026-187-01 advisory.

    New c-ares packages are available for Slackware 15.0 and -current to fix security issues.

Tenable has extracted the preceding description block directly from the c-ares security advisory.

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

ID	Name	Product	Family	Type	Severity
463526	Echo: c-ares: security update to 1.34.5-1+deb13u1+e1	Tenable Cloud Security	Echo Local Security Checks	Local	high
463526	Echo: c-ares: security update to 1.34.5-1+deb13u1+e1	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
358669	Rocky Linux 10.2 [CIQ] Security Update: c-ares / c-ares-debuginfo / c-ares-debugsource / c-ares-devel (crlsa-2026_42096)	Nessus	Rocky Linux Local Security Checks	Local	high
351470	Ubuntu 26.04 LTS : c-ares vulnerability (USN-8844-1)	Nessus	Ubuntu Local Security Checks	Local	high
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
330799	TencentOS Server 4: nodejs20 (TSSA-2026:0665)	Nessus	Tencent Local Security Checks	Local	high
329239	Oracle Linux 10 : c-ares (ELSA-2026-42096)	Nessus	Oracle Linux Local Security Checks	Local	high
329057	RockyLinux 10 : c-ares (RLSA-2026:42096)	Nessus	Rocky Linux Local Security Checks	Local	high
328790	AlmaLinux 10 : c-ares (ALSA-2026:42096)	Nessus	Alma Linux Local Security Checks	Local	high
328479	Amazon Linux 2023 : nodejs24, nodejs24-devel, nodejs24-full-i18n (ALAS2023-2026-1980)	Nessus	Amazon Linux Local Security Checks	Local	high
328473	Amazon Linux 2023 : nodejs22, nodejs22-devel, nodejs22-full-i18n (ALAS2023-2026-1981)	Nessus	Amazon Linux Local Security Checks	Local	high
328437	Fedora 43 : c-ares (2026-d70d93fcd7)	Nessus	Fedora Local Security Checks	Local	high
328366	RHEL 10 : c-ares (RHSA-2026:42096)	Nessus	Red Hat Local Security Checks	Local	high
326097	Fedora 44 : c-ares (2026-950a662010)	Nessus	Fedora Local Security Checks	Local	high
444526	Alpine: multiple c-ares packages: security update to 1.34.8-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	Local	high
444526	Alpine: multiple c-ares packages: security update to 1.34.8-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	Local	high
325394	Linux Distros Unpatched Vulnerability : CVE-2026-33630	Nessus	Misc.	Local	high
325290	Slackware Linux 15.0 / current c-ares Vulnerability (SSA:2026-187-01)	Nessus	Slackware Local Security Checks	Local	high

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