CVEs-PoC/2021/CVE-2021-21254.md

### [CVE-2021-21254](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21254)
![](https://img.shields.io/static/v1?label=Product&message=ckeditor5&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-400%20Uncontrolled%20Resource%20Consumption&color=brighgreen)

### Description

CKEditor 5 is an open source rich text editor framework with a modular architecture. The CKEditor 5 Markdown plugin (@ckeditor/ckeditor5-markdown-gfm) before version 25.0.0 has a regex denial of service (ReDoS) vulnerability. The vulnerability allowed to abuse link recognition regular expression, which could cause a significant performance drop resulting in browser tab freeze. It affects all users using CKEditor 5 Markdown plugin at version <= 24.0.0. The problem has been recognized and patched. The fix will be available in version 25.0.0.

### POC

#### Reference
No PoCs from references.

#### Github
- https://github.com/engn33r/awesome-redos-security