High 7.5Published Aug 20, 2026

CVE-2026-63495Libevent: Unbounded memory accumulation in WebSocket server via fragmented frames

Updated under an hour ago (2026-10-19 06:30 UTC)

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Every CVE for libevent

Exploited in the last 30 days

Libevent is an event notification library. From 2.2.0-alpha-dev until 2.2.2-alpha, the libevent WebSocket server in ws.c accumulates fragmented frames in evws->incomplete_frames without enforcing a total message-size limit. An unauthenticated remote client can repeatedly send fragmented WebSocket frames below WS_MAX_RECV_FRAME_SZ with FIN=0, causing the evbuffer to grow without bound until the process or host exhausts memory. This issue is fixed in version 2.2.2-alpha.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-400, CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Aug 20, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

libevent libevent libevent:libevent (from the name)	from 2.2.0-alpha-dev, < 2.2.2-alpha	CNA record

References

https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmxx-refsource-confirm
https://github.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077bx-refsource-misc
https://github.com/libevent/libevent/releases/tag/release-2.2.2-alphax-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.