Vulnerability · Published Aug 18, 2026 · Assigned by GitHub_M

CVE-2026-45126MyBB: ACP Questions state CSRF

Low 3.5

In plain English

A low-severity cross-site request forgery in mybb from mybb. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities).

Severity (CVSS 3.1)3.5Low

Exploit odds (30 days)0.2%top 93.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
mybb	mybb	< 1.8.40

Weakness: CWE-352 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

References

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