CVEvulnerability

CVE-2026-109786

5.3 MEDIUM Published 2026-10-13 Modified 2026-10-16 Official page ↗
Status
Awaiting Analysis
Published
2026-10-13
Last modified
2026-10-16
Assigner
[email protected]
CVSS 3.1 ([email protected])
5.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weaknesses
CWE-117

Description

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.

Related

Weakness · CWE (1)

  • CWE-117 Improper Output Neutralization for Logs weakness

References