Skip to content
Fencer Vulns
medium 4.0

CVE-2025-27220 json

CGI has Regular Expression Denial of Service (ReDoS) potential in Util#escapeElement

published 2025-03-03 20 mo ago modified 2026-09-10 1 mo ago also EUVD-2025-5509 , GHSA-mhwm-jh88-3gjf

cvss
4.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method.

Patch / fix

  • rubygems cgi 0.3.5.1, 0.3.7, 0.4.2
  • ruby-lang CGI 0.3.5.1, 0.3.7, 0.4.2
  • ruby3.3 Debian 14, Debian 13 3.3.7-2

debian advisories DEBIAN-CVE-2025-27220

  • ruby2.7 Ubuntu 20.04 LTS 2.7.0-5ubuntu1.18
  • ruby3.0 Ubuntu 22.04 LTS 3.0.2-7ubuntu2.10
  • ruby3.2 Ubuntu 24.04 LTS 3.2.3-1ubuntu0.24.04.5
  • ruby3.3 Ubuntu 25.10 3.3.7-1ubuntu2
  • ruby2.3 Ubuntu Pro 16.04 LTS 2.3.1-2~ubuntu16.04.16+esm10
  • ruby2.5 Ubuntu Pro 18.04 LTS 2.5.1-1ubuntu1.16+esm4

ubuntu advisories UBUNTU-CVE-2025-27220

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

  • ruby RHEL 9 3.1.7-146.module+el9.5.0+23003+a4c328ce
  • rubygems RHEL 9 3.3.27-146.module+el9.5.0+23003+a4c328ce
  • ruby-libs RHEL 9 3.1.7-146.module+el9.5.0+23003+a4c328ce
  • rubygem-pg RHEL 9 1.3.5-1.module+el9.1.0+15737+76195479
  • rubygem-irb RHEL 9 1.4.1-146.module+el9.5.0+23003+a4c328ce
  • rubygem-rbs RHEL 9 2.7.0-146.module+el9.5.0+23003+a4c328ce
  • rubygem-rss RHEL 9 0.3.1-146.module+el9.5.0+23003+a4c328ce
  • rubygem-json RHEL 9 2.6.1-146.module+el9.5.0+23003+a4c328ce

red hat advisories RHSA-2025:4488RHSA-2025:4487RHSA-2025:4063

  • ruby2.5 SLE Module for Basesystem 15 SP7 2.5.9-150700.24.3.1
  • ruby2.5 SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +13 more 2.5.9-150000.4.41.1

suse advisories SUSE-SU-2025:4264-1SUSE-SU-2025:1369-1

  • rubygem-pg AlmaLinux 9 1.3.5-1.module_el9.1.0+8+503f6fbd
  • rubygem-mysql2 AlmaLinux 9 0.5.4-1.module_el9.1.0+8+503f6fbd
  • ruby AlmaLinux 8 3.1.7-145.module_el8.10.0+3984+cf55e3df
  • rubygems AlmaLinux 8 3.3.27-145.module_el8.10.0+3984+cf55e3df
  • ruby-libs AlmaLinux 8 3.1.7-145.module_el8.10.0+3984+cf55e3df
  • rubygem-pg AlmaLinux 8 1.3.2-1.module_el8.10.0+3854+02eaa59a
  • rubygem-pg AlmaLinux 8 1.3.2-1.module_el8.9.0+3746+91b8233a
  • rubygem-irb AlmaLinux 8 1.4.1-145.module_el8.10.0+3984+cf55e3df

almalinux advisories ALSA-2025:4488ALSA-2025:4063

  • ruby Rocky Linux 9 3.1.7-146.module+el9.5.0+31847+8b291b93
  • rubygem-pg Rocky Linux 9 1.3.5-1.module+el9.5.0+31847+8b291b93
  • rubygem-mysql2 Rocky Linux 9 0.5.4-1.module+el9.5.0+31847+8b291b93
  • ruby Rocky Linux 9 3.0.7-165.el9_5
  • ruby Rocky Linux 8 3.1.7-145.module+el8.10.0+1957+16e0d1a2
  • rubygem-pg Rocky Linux 8 1.3.2-1.module+el8.10.0+1741+bdb5b6ca
  • rubygem-pg Rocky Linux 8 1.3.2-1.module+el8.10.0+1826+b62220b4
  • rubygem-abrt Rocky Linux 8 0.4.0-1.module+el8.10.0+1827+16ecb9d2

rocky linux advisories RLSA-2025:4488RLSA-2025:4487RLSA-2025:4063

  • ruby CBL-Mariner 2.0 3.1.4-9
  • ruby Azure Linux 3.0 3.3.5-3

azure linux advisories AZL-57791AZL-57938

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2025-27220 updated cvss 5.3

CGI: ReDoS in CGI::Util#escapeElement

  • Red Hat Enterprise Linux 6 ruby, ruby-ri, ruby-irb, ruby-libs, ruby-rdoc, ruby-tcltk Red Hat Enterprise Linux 7 ruby, ruby-irb, rubygems, ruby-libs, ruby-tcltk, rubygem-json, +6 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 ruby, ruby-irb, rubygems, ruby-libs, rubygem-pg, rubygem-irb, +25 more Red Hat Enterprise Linux 9 ruby, rubygems, ruby-libs, rubygem-irb, rubygem-rbs, rubygem-rss, +13 more
    affected: workaround, no fix planned “Will not fix”
  • Red Hat CodeReady Linux Builder (v. 9) ruby-doc 3.0.7-165.el9_5
    fixed: vendor fix RHSA-2025:4487
  • Red Hat Enterprise Linux AppStream (v. 8) ruby 3.1.7-145.module+el8.10.0+23011+f9d508f8, rubygem-pg 1.3.2-1.module+el8.10.0+21470+43ec8058, ruby-libs 3.1.7-145.module+el8.10.0+23011+f9d508f8, rubygems 3.3.27-145.module+el8.10.0+23011+f9d508f8, rubygem-abrt 0.4.0-1.module+el8.10.0+21470+43ec8058, rubygem-irb 1.4.1-145.module+el8.10.0+23011+f9d508f8, +17 more
    fixed: vendor fix RHSA-2025:4063
  • Red Hat Enterprise Linux AppStream (v. 9) ruby 3.0.7-165.el9_5, ruby-libs 3.0.7-165.el9_5, rubygems 3.2.33-165.el9_5, rubygem-irb 1.3.5-165.el9_5, rubygem-rbs 1.4.0-165.el9_5, rubygem-rss 0.2.9-165.el9_5, +35 more
    fixed: vendor fix RHSA-2025:4487
  • Red Hat Enterprise Linux 8 ruby, ruby-irb, rubygems, ruby-libs, rubygem-pg, rubygem-irb, +25 more
    not affected: component not present
  • Red Hat Enterprise Linux 10 ruby
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
20 mo ago

Exploit prediction

0.76% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
GitHub 3.1 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/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

Affected packages

ecosystem package affected fixed in
rubygems cgi
<0.3.5.1
>=0.3.6, <0.3.7
>=0.4.0, <0.4.2
0.3.5.1
0.3.7
0.4.2

Affected products

  • ruby-lang CGI

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.