MediumGHSA-4r62-v4vq-hr96CVE-2021-21306

Regular Expression Denial of Service (REDoS) in Marked

Published 8 Feb 2021 · Updated 10 Sept 2026

Affected package

markednpm

Affected: >=1.1.1 <2.0.0
Fixed in: 2.0.0

Update to the fixed version for your release line, for example:npm install marked@2.0.0

Details

Impact

_What kind of vulnerability is it? Who is impacted?_

Regular expression Denial of Service

A Denial of Service attack can affect anyone who runs user generated code through marked.

Patches

_Has the problem been patched? What versions should users upgrade to?_

patched in v2.0.0

Workarounds

_Is there a way for users to fix or remediate the vulnerability without upgrading?_

None.

References

_Are there any links users can visit to find out more?_

https://github.com/markedjs/marked/issues/1927 https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS

For more information

If you have any questions or comments about this advisory:

Open an issue in marked

Is GHSA-4r62-v4vq-hr96 in any of your client repos?

Checking one package by hand is fine. Checking it across forty client projects is not. NPMscan reads the lockfiles in every GitHub repo you pick, finds each project with an affected marked, and gives you the command that fixes it.

Scan a project free, no signup Or connect GitHub to scan every repo

References

Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.