CVE-2026-45126

EUVD-2026-61007

18.08.2026, 16:17

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.

CSRF

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
GitHub_M	CNA	3.5 LOW	NETWORK	LOW	LOW	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

Base Score

CVSS 3.x

EPSS Score

Percentile: Unknown

Early Detection

Affected products identified ahead of NVD analysis through intelligence sources.

Vendor	Product	Version	Source
mybb	mybb	𝑥 < 1.8.40	CNA

Common Weakness Enumeration

CWE-352 - Cross-Site Request Forgery (CSRF)
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.

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