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Vulnerability · Published Aug 21, 2026 · Assigned by GitHub_M

CVE-2026-53525WeeChat has Non-Constant-Time Password Hash Comparison in Relay Authentication

High 7.4

In plain English

A high-severity security flaw in weechat from weechat. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.4High
Exploit odds (30 days)0.4%top 62.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

WeeChat (Wee Enhanced Environment for Chat) is a free chat client. In versions 0.3.1 through 4.9.0, the WeeChat relay authentication uses non-constant-time string comparison functions (weechat_strcasecmp and strcmp) to verify password hashes and plaintext passwords. An attacker can exploit timing differences to extract the server-computed hash character by character, then authenticate using the correct hash without knowing the password. Version 4.9.1 fixes the issue.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12weechatno fix listedDEBIAN-CVE-2026-53525
Debian:13weechatno fix listedDEBIAN-CVE-2026-53525
Debian:14weechat4.9.3-1DEBIAN-CVE-2026-53525
Ubuntu:22.04:LTSweechatno fix listedUBUNTU-CVE-2026-53525
Ubuntu:24.04:LTSweechatno fix listedUBUNTU-CVE-2026-53525
Ubuntu:26.04:LTSweechatno fix listedUBUNTU-CVE-2026-53525

Affected products (as reported)

VendorProductVersions
weechat weechat >= 0.3.4, < 4.9.1

Weakness: CWE-208 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H

References