Clipboard feature vulnerability allowing to inject arbitrary HTML into the editor using paste functionality

CVE-2021-32809 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

Description

Affected packages

The vulnerability has been discovered in clipboard plugin. All plugins with clipboard plugin dependency are affected:

Impact

A potential vulnerability has been discovered in CKEditor 4 Clipboard package. The vulnerability allowed to abuse paste functionality using malformed HTML, which could result in injecting arbitrary HTML into the editor. It affects all users using the CKEditor 4 plugins listed above at version >= 4.5.2.

Patches

The problem has been recognized and patched. The fix will be available in version 4.16.2.

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 Anton Subbotin (skavans) for recognizing and reporting this vulnerability.

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2021-08-23 19:40:57 UTC
Updated
2023-02-01 05:05:57 UTC
GitHub reviewed
2021-08-23 16:49:10 UTC
NVD published
2021-08-12

EPSS Score

Score Percentile
0.24% 46.58%

CVSS Scores

Base score Version Severity Vector
4.6 3.1 —
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N 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:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

Type Value
GHSA GHSA-7889-rm5j-hpgg ↗
CVE CVE-2021-32809 ↗

CWEs

CWE id Name
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-94 Improper Control of Generation of Code ('Code Injection')

Affected packages (1)

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

Ecosystem Package Vulnerable range First patched Vulnerable functions
npm ckeditor4 >= 4.5.2, < 4.16.2 4.16.2 —

References

cvelogic Threat Intelligence