Use of Uninitialized Resource Affecting libevent package, versions <2.1.12-stable-1ubuntu0.1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.16% (5th percentile)

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  • Snyk IDSNYK-UBUNTU2204-LIBEVENT-19169712
  • published2 Sept 2026
  • disclosed20 Aug 2026

Introduced: 20 Aug 2026

CVE-2026-63381  (opens in a new tab)
CWE-908  (opens in a new tab)

How to fix?

Upgrade Ubuntu:22.04 libevent to version 2.1.12-stable-1ubuntu0.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libevent package and not the libevent package as distributed by Ubuntu. See How to fix? for Ubuntu:22.04 relevant fixed versions and status.

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 Base Scores

version 3.1