GHSA-pvmx-g8h5-cprj — high GitHub Advisory (CVE-2021-41164) in npm/ckeditor4

Description

Affected packages

The vulnerability has been discovered in the Advanced Content Filter (ACF) module and may affect all plugins used by CKEditor 4.

Impact

A potential vulnerability has been discovered in CKEditor 4 Advanced Content Filter (ACF) core module. The vulnerability allowed to inject malformed HTML bypassing content sanitization, which could result in executing JavaScript code. It affects all users using the CKEditor 4 at version < 4.17.0.

Patches

The problem has been recognized and patched. The fix will be available in version 4.17.0.

For more information

Email us at [email protected] if you have any questions or comments about this advisory.

Acknowledgements

The CKEditor 4 team would like to thank Maurice Dauer (laytonctf) for recognizing and reporting this vulnerability.

Basic information

Type: reviewed
Severity: high
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2021-11-17 21:55:10 UTC
Updated: 2023-01-27 05:00:55 UTC
GitHub reviewed: 2021-11-17 19:56:22 UTC
NVD published: 2021-11-17

Score	Percentile
0.08%	22.64%

CVSS Scores

Base score	Version	Severity	Vector
8.2	3.1	—	`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.

Identifiers

Type	Value
GHSA	GHSA-pvmx-g8h5-cprj ↗
CVE	CVE-2021-41164 ↗

CWEs

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

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
npm	ckeditor4	< 4.17.0	4.17.0	—

Advanced Content Filter (ACF) vulnerability allowing to execute JavaScript code using malformed HTML