Vulnerability Description
c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4
- https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab
- https://github.com/c-ares/c-ares/pull/1134
- https://github.com/c-ares/c-ares/releases/tag/v1.34.7
- https://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wj
- https://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wj
FAQ
What is CVE-2026-69186?
CVE-2026-69186 is a vulnerability with a CVSS score of 5.3 (MEDIUM). c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enoug...
How severe is CVE-2026-69186?
CVE-2026-69186 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-69186?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.