Medium · CVSS 5.8CVE-2026-63381

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

Answer in brief

CVE-2026-63381 records a Medium severity (CVSS 5.8) vulnerability in Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`. The current sources do not mark it as known exploited. The current feed maps libevent/libevent (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 20, 2026Updated Sep 9, 2026Source checked Oct 5, 2026First seen by HOL Aug 20, 2026Material review Sep 9, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.8
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps libevent/libevent (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
libevent/libeventgeneric	>=2.2.0-alpha <2.2.2-alpha \|\| <2.1.13	2.2.2-alpha, 2.1.13

Recommended response

Check inventory. Check lockfiles and deployed manifests for libevent/libevent.
Review the reported fix. Update libevent/libevent to 2.2.2-alpha if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 20, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 20, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.