Cloudanix VulnDB

CVE-2026-109786

Medium · 5.3

CVSS

5.3

EPSS

0.3%

Published

Oct 13, 2026

CISA due date

—

The record

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.

Affected packages

Ecosystem Package Introduced Fixed

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