FKIE_CVE-2026-45118

Vulnerability from fkie_nvd - Published: 2026-08-18 16:17 - Updated: 2026-08-18 18:17
Severity
9.3 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Summary
MyBB is free and open source forum software. Prior to 1.8.40, the Contact module does not validate a redirect URL or protocol correctly, resulting in an open redirect and reflected JavaScript code injection. contact.php accepts the redirect target from the from HTTP parameter in $mybb->input['from'] or the Referer HTTP header in $_SERVER['HTTP_REFERER'] and passes it to redirect() without sufficient verification. A javascript: URI becomes the target of the `Click here if you don't want to wait any longer` link because $force_redirect is true, allowing script execution when a victim selects the link. This issue is fixed in version 1.8.40.
References
security-advisories@github.comhttps://github.com/mybb/mybb/releases/tag/mybb_1840
security-advisories@github.comhttps://github.com/mybb/mybb/security/advisories/GHSA-wf92-5q5h-qr53
security-advisories@github.comhttps://mybb.com/versions/1.8.40
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "mybb",
          "vendor": "mybb",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.8.40"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "MyBB is free and open source forum software. Prior to 1.8.40, the Contact module does not validate a redirect URL or protocol correctly, resulting in an open redirect and reflected JavaScript code injection. contact.php accepts the redirect target from the from HTTP parameter in $mybb-\u003einput[\u0027from\u0027] or the Referer HTTP header in $_SERVER[\u0027HTTP_REFERER\u0027] and passes it to redirect() without sufficient verification. A javascript: URI becomes the target of the `Click here if you don\u0027t want to wait any longer` link because $force_redirect is true, allowing script execution when a victim selects the link. This issue is fixed in version 1.8.40."
    }
  ],
  "id": "CVE-2026-45118",
  "lastModified": "2026-08-18T18:17:34.997",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 9.3,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.8,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-45118",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-18T17:47:24.986811Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-18T16:17:06.633",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mybb/mybb/releases/tag/mybb_1840"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mybb/mybb/security/advisories/GHSA-wf92-5q5h-qr53"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://mybb.com/versions/1.8.40"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-83"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.