CVE-2021-33621
First published: Fri Nov 18 2022(Updated: )
A vulnerability was found in Ruby that allows HTTP header injection. A CGI application using the CGI library may insert untrusted input into the HTTP response header. This issue can allow an attacker to insert a newline character to split a header and inject malicious content to deceive clients.
Credit: cve@mitre.org cve@mitre.org cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/rh-ruby27-ruby | <0:2.7.8-132.el7 | 0:2.7.8-132.el7 |
| 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 | |
| rubygems/cgi | <0.1.0.2 | 0.1.0.2 |
| rubygems/cgi | >=0.2.0<0.2.2 | 0.2.2 |
| rubygems/cgi | >=0.3.0<0.3.5 | 0.3.5 |
| debian/ruby2.7 | <=2.7.4-1+deb11u1 | 2.7.4-1+deb11u3 |
| debian/ruby3.1 | 3.1.2-7+deb12u1 3.1.2-8.5 |
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Reference Links
- https://www.cve.org/CVERecord?id=CVE-2021-33621 https://nvd.nist.gov/vuln/detail/CVE-2021-33621
- https://bugzilla.redhat.com/show_bug.cgi?id=2149706
- https://access.redhat.com/errata/RHSA-2023:3821
- https://access.redhat.com/errata/RHSA-2023:3291
- https://access.redhat.com/security/cve/cve-2021-33621
- https://lists.debian.org/debian-lts-announce/2023/06/msg00012.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DQR7LWED6VAPD5ATYOBZIGJQPCUBRJBX/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/THVTYHHEOVLQFCFHWURZYO7PVUPBHRZD/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YACE6ORF2QBXXBK2V2CM36D7TZMEJVAS/
- https://security.netapp.com/advisory/ntap-20221228-0004/
- https://www.ruby-lang.org/en/news/2022/11/22/http-response-splitting-in-cgi-cve-2021-33621/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DQR7LWED6VAPD5ATYOBZIGJQPCUBRJBX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/THVTYHHEOVLQFCFHWURZYO7PVUPBHRZD/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YACE6ORF2QBXXBK2V2CM36D7TZMEJVAS/
- https://security.gentoo.org/glsa/202401-27
- https://nvd.nist.gov/vuln/detail/CVE-2021-33621
- https://hackerone.com/reports/1204695
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/cgi/CVE-2021-33621.yml
- https://github.com/advisories/GHSA-vc47-6rqg-c7f5 (Advisory)
- https://launchpad.net/bugs/cve/CVE-2021-33621
- https://www.ruby-lang.org/en/security/
- https://github.com/ruby/cgi/compare/v0.1.0.1...v0.1.0.2
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2149707
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2149710
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2149708
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2149709
- https://www.ruby-lang.org/en/news/2022/11/24/ruby-3-1-3-released/
- https://www.ruby-lang.org/en/news/2022/11/24/ruby-3-0-5-released/
- https://www.ruby-lang.org/en/news/2022/11/24/ruby-2-7-7-released/
- https://access.redhat.com/errata/RHSA-2023:7025
- https://access.redhat.com/errata/RHSA-2024:1431
- https://access.redhat.com/errata/RHSA-2024:1576
- https://access.redhat.com/errata/RHSA-2024:3500
- https://access.redhat.com/errata/RHSA-2024:3838
- https://access.redhat.com/errata/RHSA-2024:4542
- https://github.com/ruby/cgi/commit/64c5045c0a6b84fdb938a8465a0890e5f7162708
- https://github.com/ruby/cgi/commit/b46d41c36380e04f6388970b5ef05c687f4d1819
- https://security-tracker.debian.org/tracker/CVE-2021-33621
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33621
- https://ubuntu.com/security/CVE-2021-33621
Frequently Asked Questions
What is the vulnerability ID for the Ruby gem cgi.rb vulnerability?
The vulnerability ID for the Ruby gem cgi.rb vulnerability is CVE-2021-33621.
What is the severity of CVE-2021-33621?
CVE-2021-33621 has a severity rating of 8.8 (High).
Which software versions are affected by CVE-2021-33621?
Ruby gem cgi.rb versions 0.1.0.2, 0.2.x (up to 0.2.2), and 0.3.x (up to 0.3.5) are affected by CVE-2021-33621.
How can an attacker exploit CVE-2021-33621?
An attacker can exploit CVE-2021-33621 by inserting untrusted input into the HTTP response header of a CGI application using the CGI library, causing header injection and potentially injecting malicious content.
Are there any remediation steps available for CVE-2021-33621?
Yes, remediation steps are available for CVE-2021-33621. Please refer to the references provided for more information.
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