Vulnerability in Ruby-Lang Cgi
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#escapeElement method.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.0 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.008 (54.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 54.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.008 · change: +0.000
Affected products
- Ruby-Lang Cgi — versions 0, 0.3.6, 0.4.0
- Ruby-Lang Ruby — versions 3.1.0, 3.2.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- hackerone.com/reports/2890322 (Permissions Required)
- github.com/rubysec/ruby-advisory-db/blob/master/gems/cgi/CVE-2025-27220.yml (Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-27220?
- CVE-2025-27220 is a medium-severity vulnerability in Ruby-Lang Cgi, classified under Inefficient Regular Expression Complexity. CVSS score: 4.0/10. Published 2025-03-04.
- How severe is CVE-2025-27220?
- Medium severity. CVSS v3 base score is 4.0 out of 10.
- Is CVE-2025-27220 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.