What’s Vulnerable › Vulnerabilities

CVE-2026-69184: c-ares: CPU-exhaustion denial of service via unbounded DNS name compression pointer chains

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-18 · updated 2026-09-24
• Weakness: CWE-407

Description

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.

Affected products

• c-ares: before 1.34.7

References

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

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