CVE-2021-33621 HTTP response splitting in CGI
High 8.8
Published
Updated
Check this codebase for CVE-2021-33621 and fix it if it is affected.
What it is: CVE-2021-33621 is a high-severity vulnerability in Fedoraproject Fedora, published on 18 Nov 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-33621 in the wild and no public exploit code.
Affected packages and fixed versions:
- cgi (RubyGems): affected all versions; fixed in 0.1.0.2
- cgi (RubyGems): affected all versions; fixed in 0.1.0.2
- cgi (RubyGems): affected from 0.2.0; fixed in 0.2.2
- cgi (RubyGems): affected from 0.2.0; fixed in 0.2.2
- cgi (RubyGems): affected from 0.3.0; fixed in 0.3.5
- cgi (RubyGems): affected from 0.3.0; fixed in 0.3.5
- ruby (Bitnami): affected from 2.7.0; fixed in 2.7.7, 3.0.5, 3.1.3
- ruby-min (Bitnami): affected from 2.7.0; fixed in 2.7.7, 3.0.5, 3.1.3
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2021-33621/ (Markdown: https://insights.sbomify.com/CVE-2021-33621/index.md)
Attackers can perform HTTP response splitting in Ruby applications using the CGI gem, potentially modifying responses or bypassing security controls.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-33621?
CVE-2021-33621 is a high-severity vulnerability in Fedoraproject Fedora, published on 18 Nov 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-74
Which versions are affected by CVE-2021-33621?
8 open source packages ship an affected version, including cgi, ruby and ruby-min. It affects 3 products.
| Package | Affected | Fixed in |
|---|---|---|
cgi RubyGems | All versions | 0.1.0.2 |
cgi RubyGems | All versions | 0.1.0.2 |
cgi RubyGems | From 0.2.0 | 0.2.2 |
cgi RubyGems | From 0.2.0 | 0.2.2 |
cgi RubyGems | From 0.3.0 | 0.3.5 |
cgi RubyGems | From 0.3.0 | 0.3.5 |
2 more packages
ruby Bitnami | From 2.7.0 | 2.7.7, 3.0.5, 3.1.3 |
ruby-min Bitnami | From 2.7.0 | 2.7.7, 3.0.5, 3.1.3 |
Linux distribution packages (30)
ruby Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.4-161.el9_2.1 |
ruby-debuginfo Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.4-161.el9_2.1 |
ruby-debugsource Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.4-161.el9_2.1 |
ruby-default-gems Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.4-161.el9_2.1 |
ruby-devel Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.4-161.el9_2.1 |
ruby-libs Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.4-161.el9_2.1 |
ruby-libs-debuginfo Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.4-161.el9_2.1 |
rubygem-bigdecimal Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.0-161.el9_2.1 |
rubygem-bigdecimal-debuginfo Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.0.0-161.el9_2.1 |
rubygem-bundler Red Hat:rhel_eus:9.2::appstream | All versions | 0:2.2.33-161.el9_2.1 |
rubygem-io-console Red Hat:rhel_eus:9.2::appstream | All versions | 0:0.5.7-161.el9_2.1 |
rubygem-io-console-debuginfo Red Hat:rhel_eus:9.2::appstream | All versions | 0:0.5.7-161.el9_2.1 |
rubygem-irb Red Hat:rhel_eus:9.2::appstream | All versions | 0:1.3.5-161.el9_2.1 |
rubygem-json Red Hat:rhel_eus:9.2::appstream | All versions | 0:2.5.1-161.el9_2.1 |
rubygem-json-debuginfo Red Hat:rhel_eus:9.2::appstream | All versions | 0:2.5.1-161.el9_2.1 |
rubygem-minitest Red Hat:rhel_eus:9.2::appstream | All versions | 0:5.14.2-161.el9_2.1 |
rubygem-power_assert Red Hat:rhel_eus:9.2::appstream | All versions | 0:1.2.0-161.el9_2.1 |
rubygem-psych Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.3.2-161.el9_2.1 |
rubygem-psych-debuginfo Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.3.2-161.el9_2.1 |
rubygem-rake Red Hat:rhel_eus:9.2::appstream | All versions | 0:13.0.3-161.el9_2.1 |
rubygem-rbs Red Hat:rhel_eus:9.2::appstream | All versions | 0:1.4.0-161.el9_2.1 |
rubygem-rdoc Red Hat:rhel_eus:9.2::appstream | All versions | 0:6.3.3-161.el9_2.1 |
rubygem-rexml Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.2.5-161.el9_2.1 |
rubygem-rss Red Hat:rhel_eus:9.2::appstream | All versions | 0:0.2.9-161.el9_2.1 |
rubygem-test-unit Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.3.7-161.el9_2.1 |
rubygem-typeprof Red Hat:rhel_eus:9.2::appstream | All versions | 0:0.15.2-161.el9_2.1 |
rubygems Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.2.33-161.el9_2.1 |
rubygems-devel Red Hat:rhel_eus:9.2::appstream | All versions | 0:3.2.33-161.el9_2.1 |
ruby-doc Red Hat:rhel_eus:9.2::crb | All versions | 0:3.0.4-161.el9_2.1 |
ruby3.1 openSUSE:Tumbleweed | All versions | 3.1.3-1.1 |
Products include Fedoraproject Fedora, Ruby-Lang Cgi, Ruby-Lang Ruby.
How do I fix CVE-2021-33621?
Upgrade cgi to a fixed version for your release line: 0.1.0.2, 0.2.2 or 0.3.5.
Is CVE-2021-33621 being exploited?
There is no known exploitation of CVE-2021-33621 in the wild and no public exploit code.
Other vulnerabilities in Fedoraproject Fedora
Sources
Also known as ALPINE-CVE-2021-33621, BIT-ruby-2021-33621, BIT-ruby-min-2021-33621, CLEANSTART-2026-JL84667, DEBIAN-CVE-2021-33621, GHSA-vc47-6rqg-c7f5 and 9 more.