CVE-2026-69184

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.

• 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