{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "source": "REFERENCES"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "bd2a3447939d3084a5926dd66ece04649e0e0d60"
            },
            {
              "fixed": "e9942c6d19ac1709b3df7357cfb8810774c8d3ac"
            }
          ],
          "repo": "https://github.com/mybb/mybb",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-v2h7-4jp7-j6hh"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-636"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46482.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "fixed": "1.8.40"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "### Impact\nThe registration component does not validate the text-based _Security Question_ CAPTCHA correctly, allowing attackers to bypass the challenge via a specially crafted value.\n\n\n[CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N](https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)\n\n### Details\nThe public _Registration_ workflow ([`member.php?action=do_register`](https://github.com/mybb/mybb/blob/mybb_1839/member.php#L262-L307)) accepts a hidden field `question_id` — expected to match the question session identifier (`mybb_questionsessions.sid`) — and validates the challenge answer without a fail-closed fallback for invalid identifiers. If the value is blank, forged, or expired, the request continues without a question-related error.\n\n### Patches\nMyBB 1.8.(...) resolves this issue with the following changes:\n\n- Commit: https://github.com/mybb/mybb/commit/\n  - `.patch`: https://github.com/mybb/mybb/commit/.patch\n\n### References\n- Release Notes: https://mybb.com/versions/1.8.(...)/\n\n### For more information\nGo to [mybb.com/security](https://mybb.com/security/) to report possible security concerns or to learn more about security research at MyBB.\n\n### Contact\nThe security team can be reached at [security@mybb.com](mailto:security@mybb.com).",
  "id": "CVE-2026-46482",
  "modified": "2026-08-20T03:30:24.530023139Z",
  "published": "2026-08-18T15:44:59.644Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mybb/mybb/releases/tag/mybb_1840"
    },
    {
      "type": "WEB",
      "url": "https://mybb.com/versions/1.8.40"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46482.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/mybb/mybb/security/advisories/GHSA-v2h7-4jp7-j6hh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46482"
    },
    {
      "type": "FIX",
      "url": "https://github.com/mybb/mybb/commit/bd2a3447939d3084a5926dd66ece04649e0e0d60"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "MyBB: Security Question insufficient validation"
}