MyBB Forum Software Vulnerability in Admin CP Security Questions Module
CVE-2026-45126

3.5LOW

Key Information:

Vendor

Mybb

Status
Mybb
Vendor
CVE Published:
18 August 2026

What is CVE-2026-45126?

MyBB, the popular free and open-source forum software, has a vulnerability in its Admin Control Panel's Security Questions module that allows attackers to manipulate registration challenge questions without proper authorization. Specifically, prior to version 1.8.40, the module fails to correctly validate the anti-CSRF token, exposing it to same-site attack vectors. As a result, a specially crafted URL could be utilized to enable or disable registration challenge questions, undermining the integrity of user registrations. This flaw has been addressed in version 1.8.40.

Affected Version(s)

mybb < 1.8.40

References

https://github.com/mybb/mybb/security/advisories/GHSA-m42...
x_refsource_CONFIRM
https://github.com/mybb/mybb/commit/6893b395c7fa3b9e4de62...
x_refsource_MISC
https://github.com/mybb/mybb/releases/tag/mybb_1840
x_refsource_MISC

CVSS V3.1

Score:
3.5
Severity:
LOW
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.