CSRF in Mybb

CVE-2026-45129

MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP Recovery Codes module does not validate requests correctly, allowing same-site attackers to rotate a victim administrator's recovery codes with a specially crafted URL. The Admin CP Home, Preferences, Recovery Codes action=recovery_codes page regenerates Two-Factor Authentication recovery codes in mybb_adminoptions.recovery_codes on GET requests without request forgery protection. The uniquely identifying implementation details include admin/modules/home/preferences.php. This issue is fixed in version 1.8.40.

Vulnerability class: CSRF (Cross-Site Request Forgery)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.6 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L.

EPSS exploit prediction

EPSS: 0.002 (7.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 7.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-45129: held from 0.001 to 0.002.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.000

Affected products

  • Mybb — versions < 1.8.40

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-45129?
CVE-2026-45129 is a medium-severity vulnerability in Mybb, classified under Cross-Site Request Forgery (CSRF). CVSS score: 4.6/10. Published 2026-08-18.
How severe is CVE-2026-45129?
Medium severity. CVSS v3 base score is 4.6 out of 10.