CVE-2026-109786

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Source

https://cve.org/CVERecord?id=CVE-2026-109786

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-109786.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-109786

Downstream

Published

2026-10-13T02:40:13Z

Modified

2026-10-28T02:30:36Z

Severity

5.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L CVSS Calculator

Summary

[none]

Details

In fail2ban 0.10.5 through 1.1.1 before ddd879d, the sshd filter (config/filter.d/sshd.conf) accepts an "on " 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.

Database specific

{
    "cna_assigner": "mitre",
    "cwe_ids": [
        "CWE-117"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/109xxx/CVE-2026-109786.json"
}

References

Affected packages

Git / github.com/fail2ban/fail2ban

Affected ranges

Type

GIT

Repo

https://github.com/fail2ban/fail2ban

Events

Introduced

b25d8565fc23da58f97d1da649b46d27fb80b64a

Fixed

ddd879d22664904ace24e1255ac6571808c58187

Database specific

Show details

{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "0.10.5"
                },
                {
                    "last_affected": "1.1.1"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StandardRange"
        },
        {
            "range": [
                {
                    "fixed": "ddd879d22664904ace24e1255ac6571808c58187"
                }
            ],
            "source": "REFERENCES_COMMIT"
        }
    ]
}

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-109786.json"