HTTP response splitting in CGI gem for Ruby

Published: 2022-11-22
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-33621
Exploitation vector Network
Public exploit N/A
Vulnerable software
Web applications / Modules and components for CMS

Vendor Ruby

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) HTTP response splitting

EUVDB-ID: #VU69506

Risk: Medium


CVE-ID: CVE-2021-33621

CWE-ID: CWE-113 - Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')

Exploit availability: No


The vulnerability allows a remote attacker to perform HTTP splitting attacks.

The vulnerability exists due to software does not corrector process CRLF character sequences when handling cookies. A remote attacker can send specially crafted request containing CRLF sequence and make the application to send a split HTTP response.

Successful exploitation of the vulnerability may allow an attacker perform cache poisoning attack.


Install updates from vendor's website.

Vulnerable software versions

cgi: 0.1.0 - 0.3.3

CPE2.3 External links

Q & A

Can this vulnerability be exploited remotely?

Is there known malware, which exploits this vulnerability?