{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-109786",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-15T15:03:56.691809Z",
                "version": "2.0.3"
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          "dateUpdated": "2026-10-15T15:04:19.106Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unknown",
          "modules": [
            "sshd filter"
          ],
          "platforms": [
            "Linux",
            "Unix"
          ],
          "product": "fail2ban",
          "programFiles": [
            "config/filter.d/sshd.conf"
          ],
          "repo": "https://github.com/fail2ban/fail2ban",
          "vendor": "fail2ban",
          "versions": [
            {
              "lessThanOrEqual": "1.1.1",
              "status": "affected",
              "version": "0.10.5",
              "versionType": "custom"
            }
          ]
        }
      ],
      "configurations": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "The sshd jail is enabled with the stock filter.d/sshd.conf (any mode: normal, the default, extra, or aggressive). Before 1.1.1 the filter only matches log lines from a process named sshd (OpenSSH before 10, or systems that log as sshd); 1.1.1 also matches OpenSSH 10\u0027s sshd-session."
            }
          ],
          "value": "The sshd jail is enabled with the stock filter.d/sshd.conf (any mode: normal, the default, extra, or aggressive). Before 1.1.1 the filter only matches log lines from a process named sshd (OpenSSH before 10, or systems that log as sshd); 1.1.1 also matches OpenSSH 10\u0027s sshd-session."
        }
      ],
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:a:fail2ban:fail2ban:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "1.1.1",
                  "versionStartIncluding": "0.10.5",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
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              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-117",
              "description": "CWE-117 Improper Output Neutralization for Logs",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-13T02:40:13.899Z",
        "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
        "shortName": "mitre"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/fail2ban/fail2ban/commit/ddd879d22664904ace24e1255ac6571808c58187"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://coredump.ws/repos/mail-hardening.git/"
        }
      ],
      "solutions": [
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          "lang": "en",
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              "type": "text/html",
              "value": "Apply upstream commit ddd879d22664904ace24e1255ac6571808c58187, or upgrade to the first fail2ban release after 1.1.1 that contains it."
            }
          ],
          "value": "Apply upstream commit ddd879d22664904ace24e1255ac6571808c58187, or upgrade to the first fail2ban release after 1.1.1 that contains it."
        }
      ],
      "workarounds": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Override __on_port_opt and __suff in a local filter.d/sshd.local so that only an optional \"port N\" may follow the host address, as in the upstream fix: __on_port_opt = (?: port \\d+)? and __suff = %(__on_port_opt)s(?: \\[preauth\\])?\\s*. Add the administrator\u0027s own addresses to ignoreip."
            }
          ],
          "value": "Override __on_port_opt and __suff in a local filter.d/sshd.local so that only an optional \"port N\" may follow the host address, as in the upstream fix: __on_port_opt = (?: port \\d+)? and __suff = %(__on_port_opt)s(?: \\[preauth\\])?\\s*. Add the administrator\u0027s own addresses to ignoreip."
        }
      ],
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        "engine": "CVE-Request-form 0.0.1"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
    "assignerShortName": "mitre",
    "cveId": "CVE-2026-109786",
    "datePublished": "2026-10-13T02:40:13.899Z",
    "dateReserved": "2026-10-13T02:40:12.792Z",
    "dateUpdated": "2026-10-15T15:04:19.106Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}