CVE-2021-39338 MyBB Cross-Poster <= 1.0 Authenticated Stored Cross-Site Scripting
Administrators can inject arbitrary web scripts via insufficient input validation in the MyBB Cross-Poster WordPress plugin when unfiltered_html is disabled.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-39338?
CVE-2021-39338 is a medium-severity cross-site scripting vulnerability in MyBB Cross-Poster, published on 15 Oct 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2021-39338?
It affects 1 product.
Products include Mybb Cross-Poster Project Mybb Cross-Poster.
How do I fix CVE-2021-39338?
No fix has been published for CVE-2021-39338 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2021-39338 being exploited?
There is no known exploitation of CVE-2021-39338 in the wild and no public exploit code.
Sources
Also known as GHSA-p7r5-mv7j-8m3r.