Home/CVE/In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#es
CVE

CVE-2025-27220

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

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

MEDIUM · CVSS 4 EPSS 0.00246
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules3 YARA rules0
⬡

Weakness Classification

CWE-1333Inefficient Regular Expression Complexity
CWE-1333Inefficient Regular Expression Complexity
▤

Affected Products & Versions

3
ruby-lang cgi< 0.3.5.1
ruby-lang cgi>= 0.4.0 and < 0.4.2
ruby-lang cgiall versions
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
RubyGems cgi MODERATE fixed in 0.3.5.1
◈

Sigma Hunt Rules

3
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productmediumRuby on Rails Framework Exceptions
productmediumPotential Ruby Reverse Shell
productmediumRuby Inline Command Execution
▣

Scoring & Timeline

4
MEDIUM · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD04 Mar 2025 · 12:15 AM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

8
suse-csafSUSE-SU-2025:4264-1
suse-csafSUSE-SU-2025:1369-1
usnUSN-7442-1
usnUSN-7418-1
msrcCVE-2025-27220
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/cgi/CVE-2025-27220.ymlThird Party Advisory
https://hackerone.com/reports/2890322Permissions Required
https://lists.debian.org/debian-lts-announce/2025/03/msg00008.html
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