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Fencer Vulns
medium 5.3

CVE-2021-21306 json

Denial of Service in Marked

published 2021-02-08 5 y ago modified 2026-09-10 1 mo ago also GHSA-4r62-v4vq-hr96 , EUVD-2021-0532

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.5%
EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

Marked is an open-source markdown parser and compiler (npm package "marked"). In marked from version 1.1.1 and before version 2.0.0, there is a Regular expression Denial of Service vulnerability. This vulnerability can affect anyone who runs user generated code through marked. This vulnerability is fixed in version 2.0.0.

Patch / fix

  • npm marked 2.0.0
  • marked_project marked 2.0.0
  • marked Arch Linux 2.0.0-1
  • hedgedoc Arch Linux 1.8.0-1

arch linux advisories AVG-1548AVG-1908

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-21306 updated cvss 7.5

nodejs-marked: Regular expression denial of service

  • Red Hat OpenShift Service Mesh 2.0 servicemesh-grafana, servicemesh-grafana-prometheus Red Hat OpenShift Container Platform 4 openshift4/ose-grafana
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.49% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
npm marked
>=1.1.1, <2.0.0
2.0.0

Affected products

  • markedjs marked

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.