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Fencer Vulns
high 7.5

CVE-2023-31606 json

RedCloth Regular Expression Denial of Service issue

published 2023-06-06 3 y ago modified 2026-06-17 4 mo ago also GHSA-qcm3-vfq5-wfr2 , EUVD-2023-1866

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

A Regular Expression Denial of Service (ReDoS) issue was discovered in the sanitize_html function of redcloth gem v4.0.0. This vulnerability allows attackers to cause a Denial of Service (DoS) via supplying a crafted payload.

Patch / fix

  • rubygems RedCloth 4.3.3
  • ruby-redcloth Debian 14, Debian 13 4.3.3-1

debian advisories DEBIAN-CVE-2023-31606

  • ruby-redcloth Ubuntu 20.04 LTS 4.3.2-3+deb10u1build0.20.04.1
  • ruby-redcloth Ubuntu 22.04 LTS 4.3.2-4ubuntu0.22.04.1
  • ruby-redcloth Ubuntu Pro 16.04 LTS 4.2.9-5ubuntu0.1~esm1
  • ruby-redcloth Ubuntu Pro 18.04 LTS 4.3.2-3ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2023-31606

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2023-31606 updated cvss 7.5

RedCloth: Regular expression denial of service in sanitize_html function

  • Red Hat 3scale API Management Platform 2 3scale-amp-system 3scale-amp-system
    affected: no fix available

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

1.51% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/jgarber/redcloth/issues/73 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/e23e/CVE-2023-31606#readme referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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
rubygems RedCloth
<4.3.3
4.3.3

Classification

Weakness
  • CWE-1333 Inefficient Regular Expression Complexity

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.