HOMEVULNERABILITIESCVE-2021-33829
MEDIUM

CVE-2021-33829

CWE-79Published: June 9, 2021· Updated: Jun 17, 2026

6.1
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-33829 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.

From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeChanged
Impact
ConfidentialityLow
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected Vendors & Products

ckeditor1 product(s)
ckeditor
Debian1 product(s)
debian linux
Drupal1 product(s)
drupal
Fedora1 product(s)
fedora
Source: NVD CPE · 6 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

All References (12)

Quick Facts

CVE IDCVE-2021-33829
CVSS Score6.1 / 10
SeverityMEDIUM
WeaknessCWE-79
CISA KEVNo
Affected4 vendor(s)
PublishedJun 9, 2021

Related CVEs (CWE-79)

Recommended Actions

  • Apply vendor patches immediately
  • Monitor CVE-2021-33829 in threat intel feeds
  • Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.