CVE-2026-45126

3.5 lowEPSS 0.2%

Low (3.5). EPSS 0.2% chance of exploitation in the next 30 days.

MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP Security Questions module does not validate the anti-CSRF token correctly, allowing same-site attackers to enable or disable registration challenge questions with a specially crafted URL. The controller processes GET requests for the disable and enable actions to modify mybb_questions.active without verifying the my_post_key token attached by the user interface. The uniquely identifying implementation details include admin/modules/config/questions.php. This issue is fixed in version 1.8.40.

Severity

CVSS 3.1

3.5 low

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

EPSS: 0.2% chance of exploitation in the next 30 days; higher than 6% of CVEs (scores of 2026-10-31)
CWE: CWE-352
Published: 2026-08-18
Modified: 2026-09-08
Record from: the NVD, synced 2026-10-19

References

https://github.com/mybb/mybb/commit/6893b395c7fa3b9e4de6235caea0ce198c376c4f
https://github.com/mybb/mybb/releases/tag/mybb_1840
https://github.com/mybb/mybb/security/advisories/GHSA-m42q-vgx3-fqcc
https://mybb.com/versions/1.8.40

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