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CVE-2021-33829

32
FAUCET Score

CVE-2021-33829 is a medium-severity cross-site scripting (XSS) vulnerability in CKEditor 4, versions 4.14.0 through 4.16.x before 4.16.1, also affecting products like Debian and Drupal. Attackers can inject malicious JavaScript via crafted comments due to mishandling of the "--!>" sequence. While there is no evidence of active exploitation or KEV listing, a Nuclei template exists for Drupal 7 CKEditor XSS, and the vulnerability has a high FAUCET Risk Score of 97/100, despite minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.14.0, < 4.16.1CPE matchmatch criteria
cpe:2.3:a:ckeditor:ckeditor:*:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
>= 8.9.0, < 8.9.16CPE matchmatch criteria
cpe:2.3:a:drupal:drupal:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.19%
Probability of exploitation in next 30 days
EPSS Percentile
86.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Nuclei: CVE-2021-33829 · Dec 17, 2025
This CVE's current EPSS score of 0.0319 is in the 94th percentile among its peer group of 26,234 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (9)

composerpatch availablevia ghsa
Product: drupal/drupalFixed in: 9.1.9
composerpatch availablevia ghsa
Product: drupal/coreFixed in: 7.80
composerpatch availablevia ghsa
Product: drupal/coreFixed in: 8.9.16
composerpatch availablevia ghsa
Product: drupal/coreFixed in: 9.0.14
composerpatch availablevia ghsa
Product: drupal/coreFixed in: 9.1.9
composerpatch availablevia ghsa
Product: drupal/drupalFixed in: 7.80
composerpatch availablevia ghsa
Product: drupal/drupalFixed in: 8.9.16
composerpatch availablevia ghsa
Product: drupal/drupalFixed in: 9.0.14
npmpatch availablevia ghsa
Product: ckeditor4Fixed in: 4.16.1

Vendor Advisories (1)

npmGHSA-rgx6-rjj4-c388medium

ckeditor4 vulnerable to cross-site scripting

Jun 21, 2021

References

ckeditor.com / blog/ckeditor-4.16.1-with-accessibility-enhancements
PatchRelease NotesVendor Advisory
lists.debian.org / debian-lts-announce/2021/11/msg00007.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/NYA354LJP47KCVJMTUO77ZCX3ZK42G3T
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/UVOYN2WKDPLKCNILIGEZM236ABQASLGW
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/WAGNWHFIQAVCP537KFFS2A2GDG66J7XD
drupal.org / sa-core-2021-003
PatchThird Party Advisory