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GHSA-4r62-v4vq-hr96

MEDIUMFix: markedjs/marked#1864

GHSA-4r62-v4vq-hr96 is a medium-severity (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in marked. O3 Security confirms whether GHSA-4r62-v4vq-hr96 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Regular Expression Denial of Service (REDoS) in Marked

Also known asCVE-2021-21306
Published
Feb 8, 2021
Updated
Mar 13, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.

markednpm
61.4Mdownloads / week

Description

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:

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmmarked1.1.1&&< 2.0.02.0.0

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for marked. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update marked to 2.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4r62-v4vq-hr96 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-4r62-v4vq-hr96 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-4r62-v4vq-hr96. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact _What kind of vulnerability is it? Who is impacted?_ [Regular expression Denial of Service](https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS) 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/marke
O3 Security · Impact-Aware SCA

Is GHSA-4r62-v4vq-hr96 in your dependencies?

O3 detects GHSA-4r62-v4vq-hr96 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.