CVE-2021-39202: WordPress 5.8 beta: Stored Cross-Site Scripting (XSS) vulnerability in widget

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-09-09 · updated 2026-06-17
Weakness: CWE-79

Description

WordPress is a free and open-source content management system written in PHP and paired with a MySQL or MariaDB database. In affected versions the widgets editor introduced in WordPress 5.8 beta 1 has improper handling of HTML input in the Custom HTML feature. This leads to stored XSS in the custom HTML widget. This has been patched in WordPress 5.8. It was only present during the testing/beta phase of WordPress 5.8.

Affected products

WordPress: 5.8-beta1, 5.8-beta2

References

https://github.com/WordPress/wordpress-develop/security/advisories/GHSA-fr6h-3855-j297
https://hackerone.com/reports/1222797
https://github.com/WordPress/wordpress-develop/security/advisories/GHSA-fr6h-3855-j297
https://hackerone.com/reports/1222797

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