CVE-2026-33630: C-Ares

High severity, CVSS 7.5. EPSS: 0.8% chance of exploitation in the next 30 days.

c-ares is an asynchronous resolver library. From ver 1.32.3 until 1.34.7, a use-after-free / double-free in c-ares' query-completion handling. The same flaw — a query's callback being invoked while the query is still linked in the channel's internal lookup structures — is present at multiple points in the resend/finish path (timeout handling, response handling, and query dispatch). If the query, or for ares_getaddrinfo() the owning host_query, is freed as a side effect of that callback, it is then accessed and/or freed a second time. This vulnerability is fixed in ver 1.34.7.

Affected products

• C-Ares C-Ares: from 1.32.3, before 1.34.7 (fixed in 1.34.7)

Published 2026-09-03. Last modified 2026-09-09.