CVE-2026-69186c-ares: Memory-amplification denial of service via unvalidated DNS header record counts
Updated under an hour ago ()
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It affects c-ares. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Weakness (CWE)
- CWE-400
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Sep 18, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
c-ares c-ares c_ares:c_ares (from the name) | before 1.34.7 | CNA record |
References
- https://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wjx-refsource-confirm
- https://github.com/c-ares/c-ares/pull/1134x-refsource-misc
- https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4x-refsource-misc
- https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaabx-refsource-misc
- https://github.com/c-ares/c-ares/releases/tag/v1.34.7x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.