{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.10.5"
              },
              {
                "fixed": "1.1.1"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "b25d8565fc23da58f97d1da649b46d27fb80b64a"
            },
            {
              "fixed": "f60978618a101427b06924fc932b44350fec2b63"
            },
            {
              "fixed": "ddd879d22664904ace24e1255ac6571808c58187"
            }
          ],
          "repo": "https://github.com/fail2ban/fail2ban",
          "type": "GIT"
        }
      ]
    }
  ],
  "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"
  },
  "details": "In fail2ban 0.10.5 through 1.1.1 before ddd879d, the sshd filter (config/filter.d/sshd.conf) accepts an \"on \u003ctoken\u003e\" 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.",
  "id": "CVE-2026-109786",
  "modified": "2026-10-14T02:30:48.524874602Z",
  "published": "2026-10-13T02:40:13.899Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://coredump.ws/repos/mail-hardening.git/"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/109xxx/CVE-2026-109786.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109786"
    },
    {
      "type": "FIX",
      "url": "https://github.com/fail2ban/fail2ban/commit/ddd879d22664904ace24e1255ac6571808c58187"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fail2ban/fail2ban"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}