CVE-2021-33829

Name: CVE-2021-33829
Creator: NVD / NIST
Published: 2021-06-09T12:15:07.863+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 3.19%

Last modified Jun 17, 2026

CVE-2021-33829 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. A cross-site scripting (XSS) vulnerability in the HTML Data Processor in CKEditor 4 4.14.0 through 4.16.x before 4.16.1 allows remote attackers to inject executable JavaScript code through a crafted comment because --!> is mishandled.. EPSS estimates a 3.19% chance of exploitation in the next 30 days.

Description

A cross-site scripting (XSS) vulnerability in the HTML Data Processor in CKEditor 4 4.14.0 through 4.16.x before 4.16.1 allows remote attackers to inject executable JavaScript code through a crafted comment because --!> is mishandled.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

3.19%

86.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Ckeditor	Ckeditor	>= 4.14.0, < 4.16.1
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34
Fedoraproject	Fedora	35
Drupal	Drupal	>= 8.9.0, < 8.9.16
Drupal	Drupal	>= 9.0.0, < 9.0.14
Drupal	Drupal	>= 9.1.0, < 9.1.9
Debian	Debian Linux	9.0

References

Timeline

Published: Jun 9, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33829?

How severe is CVE-2021-33829?

CVE-2021-33829 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 3.19% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33829?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33829?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST