CVE-2026-33630: c-ares : Use-after-free / double-free in c-ares query-completion handling, remotely triggerable via ares_getaddrinfo() over TCP
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 aresgetaddrinfo() the owning hostquery, 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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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c-aresto a version that resolves this vulnerability.Fixed in 1.34.7Patch CVE-2026-33630 - Upgrade
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c-aresto a version that resolves this vulnerability.Fixed in 1.34.7Patch GHSA-pjmc-gx33-gc76 - Upgrade
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c-aresto a version that resolves this vulnerability.Fixed in 1.34.7Patch GHSA-jv8r-gqr9-68wj