{"apiVersion":"1.0","identifier":"CVE-2026-46482","description":"### Impact The registration component does not validate the text-based _Security Question_ CAPTCHA correctly, allowing attackers to bypass the challenge via a specially crafted value. [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) ### Details The 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. ### Patches MyBB 1.8.(...) resolves this issue with the following changes: - Commit: https://github.com/mybb/mybb/commit/ - `.patch`: https://github.com/mybb/mybb/commit/.patch ### References - Release Notes: https://mybb.com/versions/1.8.(...)/ ### For more information Go to [mybb.com/security](https://mybb.com/security/) to report possible security concerns or to learn more about security research at MyBB. ### Contact The security team can be reached at [security@mybb.com](mailto:security@mybb.com).","publishedAt":"2026-08-18T16:17:09","lastModifiedAt":"2026-08-18T18:17:38","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-46482","cvssScore":5.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","epssProbability":0.00328,"riskScore":0.55,"affectedProduct":"MyBB","affectedVersions":"unknown","vulnerabilityType":"Web app","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-46482","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-46482","en":"https://www.redsauce.net/en/cves/CVE-2026-46482","fr":"https://www.redsauce.net/fr/cves/CVE-2026-46482","pt":"https://www.redsauce.net/pt/cves/CVE-2026-46482","de":"https://www.redsauce.net/de/cves/CVE-2026-46482","sk":"https://www.redsauce.net/sk/cves/CVE-2026-46482","el":"https://www.redsauce.net/el/cves/CVE-2026-46482"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-46482"}}