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CVE-2026-69184

CVE-2026-69184 · c-ares: CPU-exhaustion denial of service via unbounded DNS name compression pointer chains

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

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.

CVSS 7.5 · High · EPSS 0.5% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • c-ares

    Versions
    • < 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:Pro:16.04:LTS

    Versions
    • 1.10.0-2
    • 1.10.0-3
    • 1.10.0-3ubuntu0.1
    • 1.10.0-3ubuntu0.2
    • 1.10.0-3ubuntu0.2+esm1
    • 1.10.0-3ubuntu0.2+esm2
    • 1.10.0-3ubuntu0.2+esm3
    Affected ranges
    • ECOSYSTEM: < 1.10.0-3ubuntu0.2+esm4

    Update to 1.10.0-3ubuntu0.2+esm4

  • c-ares Ubuntu:Pro:18.04:LTS

    Versions
    • 1.13.0-2
    • 1.13.0-3
    • 1.14.0-1
    • 1.14.0-1ubuntu0.1
    • 1.14.0-1ubuntu0.2
    • 1.14.0-1ubuntu0.2+esm1
    • 1.14.0-1ubuntu0.2+esm2
    Affected ranges
    • ECOSYSTEM: < 1.14.0-1ubuntu0.2+esm3

    Update to 1.14.0-1ubuntu0.2+esm3

  • c-ares Ubuntu:Pro:20.04:LTS

    Versions
    • 1.15.0-1build1
    • 1.15.0-1ubuntu0.1
    • 1.15.0-1ubuntu0.2
    • 1.15.0-1ubuntu0.3
    • 1.15.0-1ubuntu0.4
    • 1.15.0-1ubuntu0.5
    Affected ranges
    • ECOSYSTEM: < 1.15.0-1ubuntu0.5+esm1

    Update to 1.15.0-1ubuntu0.5+esm1

  • c-ares Ubuntu:22.04:LTS

    Versions
    • 1.17.1-1ubuntu1
    • 1.18.1-1
    • 1.18.1-1build1
    • 1.18.1-1ubuntu0.22.04.1
    • 1.18.1-1ubuntu0.22.04.2
    • 1.18.1-1ubuntu0.22.04.3
    Affected ranges
    • ECOSYSTEM: < 1.18.1-1ubuntu0.22.04.4

    Update to 1.18.1-1ubuntu0.22.04.4

  • c-ares Ubuntu:24.04:LTS

    Versions
    • 1.19.1-3
    • 1.20.1-1
    • 1.26.0-1
    • 1.27.0-1
    • 1.27.0-1.0ubuntu1
    Affected ranges
    • ECOSYSTEM: < 1.27.0-1.0ubuntu1.1

    Update to 1.27.0-1.0ubuntu1.1

  • c-ares Ubuntu:26.04:LTS

    Versions
    • 1.34.5-1
    • 1.34.6-1
    • 1.34.6-1ubuntu0.1
    Affected ranges
    • ECOSYSTEM: < 1.34.6-1ubuntu0.2

    Update to 1.34.6-1ubuntu0.2

Original sources

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