CVE-2026-63381

Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`

MEDIUM
5.8
CVSS Score
Published: August 20, 2026 at 05:50 PM UTC
Updated: October 26, 2026 at 10:10 AM UTC
1 product affected across 1 vendorLibevent

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Severity
MEDIUM5.8
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Affected range stops below 2.1.13, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.2.2-alpha, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.8MEDIUMGitHub_M
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-908

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