Resource exhaustion in libevent - #VU136939
Published: July 6, 2026
Vulnerability identifier: #VU136939
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in the WebSocket server fragmented-frame handling path in ws.c when processing fragmented WebSocket frames. A remote attacker can send a long sequence of valid fragmented frames with FIN=0 to cause a denial of service.
The issue affects applications using libevent's WebSocket server functionality, including code paths reached through evws_new_session and related APIs.
Affected software
libevent
Remediation
Install security update from vendor's website.
libevent - update to 2.2.2 alpha