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CVE-2026-63381

CVE-2026-63381 · Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`

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

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf->first, outbuf->last, or outbuf->last_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

CVSS 5.8 · Medium · EPSS 0.2% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • libevent

    Versions
    • >= 2.2.0-alpha, < 2.2.2-alpha: Affected
    • < 2.1.13: Affected

    No fix published

  • libevent Debian:12

    Versions
    • 2.1.12-stable-8
    Affected ranges
    • ECOSYSTEM: < 2.1.12-stable-8+deb12u1

    Update to 2.1.12-stable-8+deb12u1

  • libevent Debian:13

    Versions
    • 2.1.12-stable-10
    Affected ranges
    • ECOSYSTEM: < 2.1.13-stable-1~deb13u1

    Update to 2.1.13-stable-1~deb13u1

  • libevent Debian:14

    Versions
    • 2.1.12-stable-10
    • 2.1.13-stable-1~deb13u1
    Affected ranges
    • ECOSYSTEM: < 2.1.13-stable-1

    Update to 2.1.13-stable-1

  • libevent Ubuntu:Pro:18.04:LTS

    Versions
    • 2.1.8-stable-4
    • 2.1.8-stable-4build1
    Affected ranges
    • ECOSYSTEM: < 2.1.8-stable-4ubuntu0.1~esm1

    Update to 2.1.8-stable-4ubuntu0.1~esm1

  • libevent Ubuntu:Pro:20.04:LTS

    Versions
    • 2.1.8-stable-4build1
    • 2.1.11-stable-1~exp0
    • 2.1.11-stable-1
    Affected ranges
    • ECOSYSTEM: < 2.1.11-stable-1ubuntu0.1~esm1

    Update to 2.1.11-stable-1ubuntu0.1~esm1

  • libevent Ubuntu:22.04:LTS

    Versions
    • 2.1.12-stable-1
    • 2.1.12-stable-1build1
    • 2.1.12-stable-1build2
    • 2.1.12-stable-1build3
    Affected ranges
    • ECOSYSTEM: < 2.1.12-stable-1ubuntu0.1

    Update to 2.1.12-stable-1ubuntu0.1

  • libevent Ubuntu:24.04:LTS

    Versions
    • 2.1.12-stable-9
    • 2.1.12-stable-9ubuntu2
    Affected ranges
    • ECOSYSTEM: < 2.1.12-stable-9ubuntu2.1

    Update to 2.1.12-stable-9ubuntu2.1

  • libevent Ubuntu:26.04:LTS

    Versions
    • 2.1.12-stable-10build1
    • 2.1.12-stable-10build2
    Affected ranges
    • ECOSYSTEM: < 2.1.12-stable-10ubuntu0.1

    Update to 2.1.12-stable-10ubuntu0.1

Original sources

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