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.

Project Subscriptions

Vendors Products
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 09 Jul 2026 13:45:00 +0000

Type Values Removed Values Added
First Time appeared C-ares
C-ares c-ares
Vendors & Products C-ares
C-ares c-ares

Thu, 09 Jul 2026 12:15:00 +0000

Type Values Removed Values Added
Description 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.
Title c-ares: c-ares: Use-after-free / double-free in query-completion handling
Weaknesses CWE-416
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important


Projects

Sign in to view the affected projects.

cve-icon MITRE

No data.

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-07-07T00:00:00Z

Links: CVE-2026-33630 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-09T13:30:05Z

Weaknesses