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Fencer Intel
high 7.5

CVE-2021-23424 json

Regular Expression Denial of Service (ReDoS)

published 5y ago modified 4mo ago also GHSA-whgm-jr23-g3j9 , EUVD-2021-2126

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

This affects all versions of package ansi-html. If an attacker provides a malicious string, it will get stuck processing the input for an extremely long time.

Patch / fix

  • npm ansi-html 0.0.8
  • ansi-html_project ansi-html 0.0.8

Is CVE-2021-23424 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2021-23424 updated cvss 7.5

nodejs-ansi-html: ReDoS via crafted string

  • Red Hat OpenShift Service Mesh 1 servicemesh-prometheus
    affected: no fix planned “Out of support scope”
  • Red Hat OpenShift Service Mesh 2.0 servicemesh-prometheus
    affected: no fix available
  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/console-rhel8, rhacm2/search-ui-rhel8
    affected: no fix available “Fix deferred”
  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/kui-web-terminal-rhel8
    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

1.77% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/Tjatse/ansi-html/issues/19 referenced PoC, tagged "exploit" by a source, unverified
  • snyk.io https://snyk.io/vuln/SNYK-JS-ANSIHTML-1296849 referenced PoC, tagged "exploit" by a source, unverified
  • snyk.io https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1567198 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm ansi-html
<0.0.8
0.0.8

Affected products

  • n/a ansi-html

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel 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.