Use-After-Free Vulnerability in c-ares Asynchronous Resolver Library
CVE-2026-33630

7.5HIGH

Key Information:

Vendor

C-ares

Status
C-ares
Vendor
CVE Published:
3 September 2026

What is CVE-2026-33630?

The c-ares asynchronous resolver library exhibits a use-after-free and double-free vulnerability in its query-completion handling mechanism. This flaw exists due to callbacks being called while queries remain linked within the internal lookup structures of the resolver. This can lead to erroneous access or repeated freeing of the same memory in a number of scenarios, including during timeout actions and response handling. The vulnerability affects versions 1.32.3 through 1.34.6 and has been resolved in version 1.34.7.

Affected Version(s)

c-ares >= 1.32.3, < 1.34.7

References

https://github.com/c-ares/c-ares/security/advisories/GHSA...
x_refsource_CONFIRM
https://github.com/c-ares/c-ares/commit/d823199b688052dcd...
x_refsource_MISC
https://github.com/c-ares/c-ares/releases/tag/v1.34.7
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.