CVE-2021-21254: Regular expression Denial of Service in Markdown plugin
First published: Fri Jan 29 2021(Updated: )
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.
Credit: security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Ckeditor Ckeditor5 | <25.0.0 |
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Reference Links
Frequently Asked Questions
What is CVE-2021-21254?
CVE-2021-21254 is a regex denial of service (ReDoS) vulnerability in the CKEditor 5 Markdown plugin before version 25.0.0.
How does CVE-2021-21254 impact CKEditor 5?
CVE-2021-21254 allows an attacker to abuse the link recognition regular expression, resulting in a denial of service (DoS) attack.
What software versions are affected by CVE-2021-21254?
CKEditor 5 versions up to and excluding 25.0.0 are affected by CVE-2021-21254.
What is the severity of CVE-2021-21254?
CVE-2021-21254 has a severity rating of 6.5, which is considered medium.
How do I fix CVE-2021-21254?
To fix CVE-2021-21254, update the CKEditor 5 Markdown plugin to version 25.0.0 or higher.
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