---
id: CVE-2026-45129
title: MyBB is free and open source forum software
summary: >-
  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
  crafte…
severity: medium
cvss: 4.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L'
cwe:
  - CWE-352
published: '2026-08-18'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T21:02:26.047'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-45129'
references:
  - url: >-
      https://github.com/mybb/mybb/commit/d2d9e47b53d85101cf25cb47e882bc7ba76355a4
    label: security-advisories@github.com
  - url: 'https://github.com/mybb/mybb/releases/tag/mybb_1840'
    label: security-advisories@github.com
  - url: 'https://github.com/mybb/mybb/security/advisories/GHSA-75vg-6wgp-mcc9'
    label: security-advisories@github.com
  - url: 'https://mybb.com/versions/1.8.40'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00139
epssPercentile: 0.0364
ingestedAt: '2026-09-08T21:11:12.280Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.