CVE-2021-33621

Name: CVE-2021-33621
Creator: NVD / NIST
Published: 2022-11-18T23:15:18.987+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 2.29%

Last modified Jun 17, 2026

CVE-2021-33621 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. The cgi gem before 0.1.0.2, 0.2.x before 0.2.2, and 0.3.x before 0.3.5 for Ruby allows HTTP response splitting. This is relevant to applications that use untrusted user input either to generate an HTTP response or to create a CGI::Cookie object.. EPSS estimates a 2.29% chance of exploitation in the next 30 days.

Description

The cgi gem before 0.1.0.2, 0.2.x before 0.2.2, and 0.3.x before 0.3.5 for Ruby allows HTTP response splitting. This is relevant to applications that use untrusted user input either to generate an HTTP response or to create a CGI::Cookie object.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

2.29%

81.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-74

Affected Software

Vendor	Product	Versions
Ruby-Lang	Cgi	< 0.1.0.2
Ruby-Lang	Cgi	>= 0.2.0, < 0.2.2
Ruby-Lang	Cgi	>= 0.3.0, < 0.3.5
Fedoraproject	Fedora	35
Fedoraproject	Fedora	36
Fedoraproject	Fedora	37
Ruby-Lang	Ruby	>= 2.7.0, < 2.7.7
Ruby-Lang	Ruby	>= 3.0.0, < 3.0.5
Ruby-Lang	Ruby	>= 3.1.0, < 3.1.3

References

Timeline

Published: Nov 18, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33621?

How severe is CVE-2021-33621?

CVE-2021-33621 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 2.29% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33621?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33621?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST