CVE-2026-109786In 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.
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Weakness (CWE)
- CWE-117
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- mitre
- NVD analysis
- Awaiting Analysis
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 13, 2026
Affected products
fail2ban fail2ban fail2ban:fail2ban (from the name) | from 0.10.5 through 1.1.1 | CNA record |
References
- https://github.com/fail2ban/fail2ban/commit/ddd879d22664904ace24e1255ac6571808c58187patch
- https://coredump.ws/repos/mail-hardening.git/related
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.