CVE-2026-63495

high

Description

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.

References

https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx

https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha

https://github.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077b

Details

Source: Mitre, NVD

Published: 2026-08-20

Updated: 2026-08-20

Risk Information

CVSS v2

Base Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C

Severity: High

CVSS v3

Base Score: 7.5

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

Severity: High

EPSS

EPSS: 0.00432