CVE-2026-63495

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 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.6% chance of exploitation in the next 30 days; higher than 48% of CVEs (scores of 2026-10-25)

CWEs

CWE-400, CWE-770

Published

2026-08-20

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

References

• https://github.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077b
• https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
• https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx
• https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx

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