CVE-2026-53524

WeeChat has a Decompression Bomb in Relay WebSocket (DoS)

State: Published
Severity: 6.5 Medium
Published: Aug 21, 2026
Updated: Aug 24, 2026
Reserved: Jun 9, 2026

Description

WeeChat (Wee Enhanced Environment for Chat) is a free chat client. In versions 4.3.0 through 4.9.0, the WeeChat relay module's WebSocket permessage-deflate decompression function relay_websocket_inflate() has no upper bound on output size. An authenticated relay user can send a small compressed WebSocket frame (~100 bytes) that decompresses to gigabytes, exhausting all server memory and crashing the entire WeeChat process. The api protocol enables permessage-deflate and requires authentication before WebSocket upgrade. Version 4.9.1 patches the issue.

Scores

CVSS	Score	Vector	Source
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H	GitHub_M

Weaknesses

CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

Affected Products

Product	Versions
weechatweechat	>= 4.3.0, < 4.9.1Affected

References

https://github.com/weechat/weechat/security/advisories/GHSA-v2v4-45wm-5cr3

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.