Vulnerability · Published Oct 15, 2021 · Assigned by Wordfence

CVE-2021-39338MyBB Cross-Poster <= 1.0 Authenticated Stored Cross-Site Scripting

Medium 5.5

In plain English

A medium-severity cross-site scripting in MyBB Cross-Poster from MyBB Cross-Poster. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 61% of all known vulnerabilities).

Severity (CVSS 3.1)5.5Medium

Exploit odds (30 days)0.9%top 38.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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.

Affected products (as reported)

Vendor	Product	Versions
MyBB Cross-Poster	MyBB Cross-Poster	1.0 – through 1.0

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N

References

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