c-ares: c-ares: Use-after-free / double-free in query-completion handling

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.

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

  CVE-2026-33630


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

  - c-ares: c-ares: Use-after-free / double-free in query-completion handling (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
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	critical
444526	Alpine: multiple c-ares packages: security update to 1.34.8-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	Local	critical
444526	Alpine: multiple c-ares packages: security update to 1.34.8-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	Local	critical
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	critical

Detections

Analytics

CVE-2026-33630

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Tenable Plugins

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