Improper handling of highly compressed data in WeeChat - CVE-2026-53524
Published: September 8, 2026
Vulnerability identifier: #VU147387
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-53524
CWE-ID: CWE-409
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper handling of highly compressed data in the relay module\'s relay_websocket_inflate() function when decompressing WebSocket permessage-deflate frames. A remote user can send a small compressed WebSocket frame that expands to exhaust process memory to cause a denial of service.
The relay api protocol requires authentication before the WebSocket upgrade and enables permessage-deflate by default.
Affected software
WeeChat
How to mitigate CVE-2026-53524
Install security update from vendor's website.
WeeChat - update to 4.9.1