CVE-2021-41165: HTML comments vulnerability allowing to execute JavaScript code

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-11-17 · updated 2026-06-17
Weakness: CWE-79

Description

CKEditor4 is an open source WYSIWYG HTML editor. In affected version a vulnerability has been discovered in the core HTML processing module and may affect all plugins used by CKEditor 4. The vulnerability allowed to inject malformed comments 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.

Affected products

ckeditor4: before 4.17.0 — fixed in 4.17.0
Drupal: from 8.9.0 before 8.9.20; from 9.1.0 before 9.1.14; from 9.2.0 before 9.2.9 — fixed in 8.9.20, 9.1.14, 9.2.9
Oracle Corporation Oracle Agile PLM: 9.3.6
Oracle Corporation Application Express: before 22.1 — fixed in 22.1
Oracle Banking Apis: from 18.1 through 18.3; 19.1, 19.2, 20.1, 21.1
Oracle Corporation Banking Digital Experience: from 18.1 through 18.3; 19.1, 19.2, 20.1, 21.1
Oracle Corporation Oracle Commerce Guided Search / Oracle Commerce Experience Manager: 11.3.2
Oracle Corporation PeopleSoft Enterprise PT PeopleTools: 8.58, 8.59
Oracle Corporation Oracle WebCenter Portal: 12.2.1.3.0, 12.2.1.4.0

How to fix

Upgrade to a fixed version: ckeditor4 4.17.0; Drupal 8.9.20, 9.1.14, 9.2.9; Oracle Corporation Application Express 22.1. Check the vendor advisory for mitigations.

References

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