MEDIUM 5.3 NVD
CVE-2026-109786
In fail2ban 0.10.5 through 1.1.1 before ddd879d, the sshd filter (config/filter.d/sshd.conf) accepts an "on <token>" suffix after the host address. Because Open
In fail2ban 0.10.5 through 1.1.1 before ddd879d, the sshd filter (config/filter.d/sshd.conf) accepts an "on <token>" suffix after the host address. Because OpenSSH logs the offered username verbatim, a remote unauthenticated attacker can use a username such as "x VICTIM-SOURCE-IP-ADDRESS on" to make fail2ban associate failed login attempts with an arbitrary source IP address and ban it (e.g., to block logins from a legitimate user). The default filter mode is affected.
References
- https://coredump.ws/repos/mail-hardening.git/
- https://github.com/fail2ban/fail2ban/commit/ddd879d22664904ace24e1255ac6571808c58187
This medium severity vulnerability with a CVSS score of 5.3 was published on 2026-10-13 via NVD.
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