CVE-2026-69184

HIGH 7.5

c-ares: CPU-exhaustion denial of service via unbounded DNS name compression pointer chains

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_name_parse() enforces backward DNS compression pointers but does not bound the total pointer hops or assembled name length. A malicious DNS server can send a response containing a long descending pointer chain and many resource records whose NAME or RDATA fields refer to the chain, causing repeated decompression work that grows quadratically with message size. A single crafted response can stall the single-threaded c-ares event loop and deny DNS resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7.

CWE	CWE-407
Vendor	c-ares
Product	c-ares
Published	Sep 18, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

c-ares / c-ares

< 1.34.7

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/c-ares/c-ares/security/advisories/GHSA-pjmc-gx33-gc76 github.com: https://github.com/c-ares/c-ares/pull/1164 github.com: https://github.com/c-ares/c-ares/pull/1210 github.com: https://github.com/c-ares/c-ares/commit/5c8341ba6ff3a8e4e4dfd616f8ed0418838b8b7b github.com: https://github.com/c-ares/c-ares/commit/f1288bbc70e9a1e0a77134c2382157e52d326aea github.com: https://github.com/c-ares/c-ares/releases/tag/v1.34.7