Home/CVE/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
CVE

CVE-2021-33829

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

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.

MEDIUM · CVSS 6.1 EPSS 0.65532
Act now
  • EPSS ≥ 0.50 - high probability of exploitation in the next 30 days
  • EPSS percentile: top 1% of all CVEs by exploitation likelihood
  • Public exploit or PoC is available
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
▤

Affected Products & Versions

6
ckeditor>= 4.14.0 and < 4.16.1
fedoraproject fedoraall versions
drupal>= 8.9.0 and < 8.9.16
drupal>= 9.0.0 and < 9.0.14
drupal>= 9.1.0 and < 9.1.9
debian linuxall versions
▤

Affected Packages

3
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Packagist drupal/core MODERATE fixed in 7.80
Packagist drupal/drupal MODERATE fixed in 7.80
npm ckeditor4 MODERATE fixed in 4.16.1
⚠

Public Exploits & PoCs

1
nucleiDrupal 7 CKEditor XSSmedium
▣

Scoring & Timeline

6.1
MEDIUM · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD09 Jun 2021 · 12:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
⚑

Vendor Advisories

2
usnUSN-5340-2
usnUSN-5340-1
🔗

References & Sources

6
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://ckeditor.com/blog/ckeditor-4.16.1-with-accessibility-enhancements/#improvements-for-comments-in-html-parserPatchRelease NotesVendor Advisory
https://lists.debian.org/debian-lts-announce/2021/11/msg00007.htmlMailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NYA354LJP47KCVJMTUO77ZCX3ZK42G3T/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UVOYN2WKDPLKCNILIGEZM236ABQASLGW/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WAGNWHFIQAVCP537KFFS2A2GDG66J7XD/
https://www.drupal.org/sa-core-2021-003PatchThird Party Advisory
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