🛡️ CVE-2021-41164 — ckeditor4

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-79 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Advanced Content Filter (ACF) vulnerability allowing to execute JavaScript code using malformed HTML

Affected packages

The vulnerability has been discovered in the Advanced Content Filter (ACF) module and may affect all plugins used by CKEditor 4.

Impact

A potential vulnerability has been discovered in CKEditor 4 Advanced Content Filter (ACF) core module. 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.

Patches

The problem has been recognized and patched. The fix will be available in version 4.17.0.

For more information

Email us at security@cksource.com if you have any questions or comments about this advisory.

Acknowledgements

The CKEditor 4 team would like to thank Maurice Dauer ([laytonctf](https://twitter.com/laytonctf)) for recognizing and reporting this vulnerability.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. A user must be tricked into taking some action. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity low, availability low.

Weakness class

CVE-2021-41164 is classified as CWE-79: Cross-site Scripting (XSS). User-supplied data is written into a page without escaping, so attacker script runs in the browser of anyone who views it.

Affected software

CVE-2021-41164 is recorded against 2 packages.

  • ckeditor4
  • drupal

Timeline and source

Published on 17 November 2021 and last revised on 8 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Package)
github.com (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
www.drupal.org (Web)
www.oracle.com (Web)
www.oracle.com (Web)
www.oracle.com (Web)

CVE-2021-41164 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:L
CWE CWE-79
Public Exploit ✅ No
Source OSV
Published 2021-11-17
Updated 2026-08-12
Modified 2026-07-08
Fix URL N/A

Affected Packages

Software From version Fixed in
ckeditor4 — —
drupal — —

Similar Threats

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