CVE-2021-39338

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

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.

Remediation

Solution:

  • Uninstall plugin from WordPress site.

Category

5.5
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.41%
Third-Party Advisory github.com Third-Party Advisory wordpress.org Third-Party Advisory wordfence.com
Affected: MyBB Cross-Poster MyBB Cross-Poster
Published at:
Updated at:

References

Link Tags
https://www.wordfence.com/vulnerability-advisories/#CVE-2021-39338 third party advisory
https://github.com/BigTiger2020/word-press/blob/main/MyBB%20Cross-Poster.md third party advisory exploit
https://plugins.trac.wordpress.org/browser/mybb-cross-poster/trunk/classes/MyBBXPSettings.php third party advisory patch

Frequently Asked Questions

What is the severity of CVE-2021-39338?
CVE-2021-39338 has been scored as a medium severity vulnerability.
How to fix CVE-2021-39338?
To fix CVE-2021-39338: Uninstall plugin from WordPress site.
Is CVE-2021-39338 being actively exploited in the wild?
It is possible that CVE-2021-39338 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-39338?
CVE-2021-39338 affects MyBB Cross-Poster MyBB Cross-Poster.
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