---
id: CVE-2026-53524
title: WeeChat (Wee Enhanced Environment for Chat) is a free chat client
summary: >-
  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
  siz…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-409
published: '2026-08-21'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:06:39.057'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53524'
references:
  - url: 'https://github.com/weechat/weechat/security/advisories/GHSA-v2v4-45wm-5cr3'
    label: security-advisories@github.com
  - url: 'https://github.com/weechat/weechat/security/advisories/GHSA-v2v4-45wm-5cr3'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00484
epssPercentile: 0.39034
ingestedAt: '2026-09-09T21:22:45.549Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.