c-ares : Use-after-free / double-free in c-ares query-completion handling, remotely triggerable via ares_getaddrinfo() over TCP

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-33630
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-03 19:17:27 UTC
Updated2026-09-05 03:17:15 UTC
Descriptionc-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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.004520000 probability, percentile 0.377580000 (date 2026-09-04)

Problem Types: CWE-415 | CWE-416 | CWE-415 CWE-415: Double Free | CWE-416 CWE-416: Use After Free

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA C-ares C-ares affected >= 1.32.3, < 1.34.7 Not specified

References

ReferenceSourceLinkTags
github.com/c-ares/c-ares/commit/1fa3b86a0b8d18fe7b60f3228a01d770feb026bc [email protected] github.com
github.com/c-ares/c-ares/commit/d823199b688052dcdc1646f2ab4cb8c16b1c644a [email protected] github.com
github.com/c-ares/c-ares/pull/1237 [email protected] github.com
github.com/c-ares/c-ares/releases/tag/v1.34.7 [email protected] github.com
github.com/c-ares/c-ares/security/advisories/GHSA-6wfj-rwm7-3542 [email protected] github.com
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