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CVE-2026-109786

fail2ban / fail2ban PUBLISHED

Description (CNA)

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 (CNA)

Vendor / productVersions
fail2ban / fail2banaffected 0.10.5 through 1.1.1

CWE

CWE-117

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.