Authentication bypass using an alternate path or channel in WeeChat - CVE-2026-86036
Published: September 8, 2026
Vulnerability identifier: #VU147384
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-86036
CWE-ID: CWE-288
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to gain an authenticated relay session without knowing the relay password.
The vulnerability exists due to improper authentication in the relay_auth_password_hash() function when processing hash authentication submissions that specify the plain password hash algorithm. A remote attacker can submit crafted authentication data specifying the plain algorithm to gain an authenticated relay session without knowing the relay password.
Exploitation requires a reachable api or weechat relay listener with a password configured and the default password-hash algorithm allow-list.
Affected software
WeeChat
How to mitigate CVE-2026-86036
Install security update from vendor's website.
WeeChat - update to 4.9.4