Vulnerability · Published Aug 18, 2026 · Assigned by GitHub_M

CVE-2026-45128MyBB: ACP Users View Manager default 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 ACP Users View Manager module does not validate requests correctly, allowing same-site attackers to change a victim administrator's default user list view by embedding a specially crafted URL. The Set as Default control named set_default in Admin CP, Users & Groups, Users, View Manager changes the administrator's default view on GET requests without request forgery protection. The uniquely identifying implementation details include Users & Groups → Users → View Manager, and admin/inc/functions_view_manager.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-m6hr-25cj-p58q x_refsource_CONFIRM
https://github.com/mybb/mybb/commit/736a2bcbc7cc104df8ae6c0a160aa3917a1ceec0 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