CVE-2021-39338

MyBB Cross-Poster <= 1.0 Authenticated Stored Cross-Site Scripting

Published Oct 15, 2021 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
The MyBB Cross-Poster WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via several parameters found in the ~/classes/MyBBXPSettings.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 1.0. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.

Analysis

No analysis available yet

Remediation

Vendor Solution

Uninstall plugin from WordPress site.

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2021-25699 The MyBB Cross-Poster WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via several parameters found in the ~/classes/MyBBXPSettings.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 1.0. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Weaknesses
  • CWE-79

    Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Sources

Status
PUBLISHED
Assigner
Wordfence
Published
Updated
Mar 31, 2025, 5:59 PM
Reserved
Aug 20, 2021, 12:00 AM
Status
Modified
Published
Oct 15, 2021, 1:15 PM
Modified
Jun 17, 2026, 4:03 AM