SB2026090843 - Multiple vulnerabilities in WeeChat

Description

This security bulletin contains information about 2 vulnerabilities.

1) Information Exposure Through Timing Discrepancy (CVE-ID: CVE-2026-53525)

CWE-ID: CWE-208 - Information Exposure Through Timing Discrepancy

CVSSv4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to bypass authentication.

The vulnerability exists due to observable timing discrepancies in relay authentication password comparisons when processing authentication attempts. A remote attacker can measure response times for crafted authentication attempts to derive an expected hash and bypass authentication.

SHA- and PBKDF2-based authentication variants are affected, as is plaintext authentication when enabled.

2) Improper handling of highly compressed data (CVE-ID: CVE-2026-53524)

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

CVSSv4: 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]

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.

Remediation

Install update from vendor's website.

References

• https://github.com/weechat/weechat/security/advisories/GHSA-vhv8-g2r9-cwcc
• https://github.com/weechat/weechat/security/advisories/GHSA-v2v4-45wm-5cr3