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CVE-2026-53524— WeeChat has a Decompression Bomb in Relay WebSocket (DoS)

Quick assessment

Affected
weechat weechat
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

WeeChat是WeeChat团队开源的一款可扩展的即时聊天客户端应用程序。 WeeChat 4.3.0版本至4.9.0版本存在资源管理错误漏洞，该漏洞源于WebSocket permessage-deflate解压缩函数relay_websocket_inflate()对输出大小没有上限，可能导致经过身份验证的中继用户发送小的压缩WebSocket帧，耗尽服务器内存并崩溃整个WeeChat进程，造成拒绝服务。

CVSS 6.5 · Medium EPSS 0.48% · P40

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

Affected Version Matrix 1

VendorProduct Version RangeStatus
weechat weechat >= 4.3.0, < 4.9.1 affected
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I. Basic Information for CVE-2026-53524

Vulnerability Information
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Vulnerability Title
WeeChat has a Decompression Bomb in Relay WebSocket (DoS)
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对高度压缩数据的处理不恰当(数据放大攻击)
Source: CVE Program / CVE List V5
Vulnerability Title
WeeChat 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
WeeChat是WeeChat团队开源的一款可扩展的即时聊天客户端应用程序。 WeeChat 4.3.0版本至4.9.0版本存在资源管理错误漏洞，该漏洞源于WebSocket permessage-deflate解压缩函数relay_websocket_inflate()对输出大小没有上限，可能导致经过身份验证的中继用户发送小的压缩WebSocket帧，耗尽服务器内存并崩溃整个WeeChat进程，造成拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
weechat weechat >= 4.3.0, < 4.9.1 -

II. Public POCs for CVE-2026-53524

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III. Intelligence Information for CVE-2026-53524

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Vendor Advisories for CVE-2026-53524 (1)

IV. Related Vulnerabilities

Same product: weechat
Same vendor: weechat
Same weakness: CWE-409

V. Comments for CVE-2026-53524

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