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CVE-2026-33630

CVE-2026-33630 · c-ares : Use-after-free / double-free in c-ares query-completion handling, remotely triggerable via ares_getaddrinfo() over TCP

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 7.5 · High · EPSS 0.8% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • c-ares

    Versions
    • >= 1.32.3, < 1.34.7: Affected

    No fix published

  • c-ares Debian:13

    Versions
    • 1.34.5-1
    • 1.34.5-1+deb13u1
    • 1.34.6-1
    • 1.34.7-1
    • 1.34.8-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • c-ares Debian:14

    Versions
    • 1.34.5-1
    • 1.34.6-1
    Affected ranges
    • ECOSYSTEM: < 1.34.7-1

    Update to 1.34.7-1

  • c-ares Ubuntu:25.10

    Versions
    • 1.34.4-2.1
    • 1.34.5-1
    • 1.34.5-1ubuntu0.1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • c-ares Ubuntu:26.04:LTS

    Versions
    • 1.34.5-1
    • 1.34.6-1
    Affected ranges
    • ECOSYSTEM: < 1.34.6-1ubuntu0.1

    Update to 1.34.6-1ubuntu0.1

Original sources

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