PT-2021-22544 · WordPress · Mybb Cross-Poster

Published 2021-10-15 · Updated 2021-10-20 · CVE-2021-39338

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N

Name of the Vulnerable Software and Affected Versions: MyBB Cross-Poster WordPress plugin versions up to and including 1.0

Description: The issue arises from insufficient input validation and sanitization via several parameters in the ~/classes/MyBBXPSettings.php file, allowing attackers with administrative user access to inject arbitrary web scripts. This affects multi-site installations where unfiltered html is disabled for administrators, and sites where unfiltered html is disabled.

Recommendations: For versions up to and including 1.0, update to a version that addresses the insufficient input validation and sanitization issue. As a temporary workaround, consider restricting access to the ~/classes/MyBBXPSettings.php file to minimize the risk of exploitation. Restrict the use of parameters in the ~/classes/MyBBXPSettings.php file that are used for input validation and sanitization until a patch is available.

Exploit

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2021-39338

Affected Products

Mybb Cross-Poster

References · 6

• 🔥 https://github.com/BigTiger2020/word-press/blob/main/MyBB%20Cross-Poster.md · Exploit
• https://plugins.trac.wordpress.org/browser/mybb-cross-poster/trunk/classes/MyBBXPSettings.php · Patch
• https://osv.dev/vulnerability/CVE-2021-39338 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-39338 · Security Note
• https://wordfence.com/vulnerability-advisories/#CVE-2021-39338 · Note
• https://t.me/cibsecurity/30617 · Telegram Post