CVE-2021-41819: High severity ruby-lang Cgi Ruby vulnerability

Published Nov 24, 2021
·
Updated

A flaw was found in Ruby. RubyGems cgi gem could allow a remote attacker to conduct spoofing attacks caused by the mishandling of security prefixes in cookie names in the CGI::Cookie.parse function. By sending a specially-crafted request, an attacker could perform cookie prefix spoofing attacks.

Other sources

CGI::Cookie.parse in Ruby through 2.6.8 mishandles security prefixes in cookie names. This also affects the CGI gem prior to versions 0.3.1, 0.2.1, 0.1.1, and 0.1.0.1 for Ruby.

— GitHub

CGI::Cookie.parse in Ruby through 2.6.8 mishandles security prefixes in cookie names. This also affects the CGI gem through 0.3.0 for Ruby.

The old versions of CGI::Cookie.parse applied URL decoding to cookie names. An attacker could exploit this vulnerability to spoof security prefixes in cookie names, which may be able to trick a vulnerable application. By this fix, CGI::Cookie.parse no longer decodes cookie names. Note that this is an incompatibility if cookie names that you are using include non-alphanumeric characters that are URL-encoded. This is the same issue of CVE-2020-8184.

Reference: https://www.ruby-lang.org/en/news/2021/11/24/cookie-prefix-spoofing-in-cgi-cookie-parse-cve-2021-41819/

— Red Hat

Affected Software

33 affected componentsFixes available
redhat/rh-ruby26-ruby<0:2.6.9-120.el7
0:2.6.9-120.el7
redhat/rh-ruby30-ruby<0:3.0.4-149.el7
0:3.0.4-149.el7
redhat/rh-ruby27-ruby<0:2.7.6-131.el7
0:2.7.6-131.el7
rubygems/cgi<0.1.0.1
0.1.0.1
rubygems/cgi=0.2.0
0.2.1
rubygems/cgi=0.3.0
0.3.1
ruby-lang Cgi Ruby=0.1.0
ruby-lang Cgi Ruby=0.2.0
ruby-lang Cgi Ruby=0.3.0
ruby-lang Ruby<=2.6.8
ruby-lang Ruby>=2.7.0<2.7.5
ruby-lang Ruby>=3.0.0<3.0.3
redhat Software Collections
redhat Enterprise Linux=8.0
Debian Debian Linux=9.0
Debian Debian Linux=10.0
Debian Debian Linux=11.0
SUSE Linux Enterprise=11.0-sp1
SUSE Linux Enterprise=12.0
SUSE Linux Enterprise=15.0
openSUSE Factory
openSUSE Leap=15.2
Fedoraproject Fedora=34
Fedoraproject Fedora=35
redhat/cgi<0.3.1
0.3.1
redhat/cgi<0.2.1
0.2.1
redhat/cgi<0.1.1
0.1.1
redhat/ruby<3.0.3
3.0.3
redhat/ruby<2.7.5
2.7.5
redhat/ruby<2.6.9
2.6.9
debian/ruby2.3
debian/ruby2.5
debian/ruby3.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/rh-ruby26-ruby to a version that resolves this vulnerability.

    Fixed in 0:2.6.9-120.el7
  2. Upgrade

    Upgrade redhat/rh-ruby30-ruby to a version that resolves this vulnerability.

    Fixed in 0:3.0.4-149.el7
  3. Upgrade

    Upgrade redhat/rh-ruby27-ruby to a version that resolves this vulnerability.

    Fixed in 0:2.7.6-131.el7
  4. Upgrade

    Upgrade rubygems/cgi to a version that resolves this vulnerability.

    Fixed in 0.1.0.1
  5. Upgrade

    Upgrade rubygems/cgi to a version that resolves this vulnerability.

    Fixed in 0.2.1
  6. Upgrade

    Upgrade rubygems/cgi to a version that resolves this vulnerability.

    Fixed in 0.3.1
  7. Upgrade

    Upgrade redhat/cgi to a version that resolves this vulnerability.

    Fixed in 0.3.1
  8. Upgrade

    Upgrade redhat/cgi to a version that resolves this vulnerability.

    Fixed in 0.2.1
  9. Upgrade

    Upgrade redhat/cgi to a version that resolves this vulnerability.

    Fixed in 0.1.1
  10. Upgrade

    Upgrade redhat/ruby to a version that resolves this vulnerability.

    Fixed in 3.0.3
  11. Upgrade

    Upgrade redhat/ruby to a version that resolves this vulnerability.

    Fixed in 2.7.5
  12. Upgrade

    Upgrade redhat/ruby to a version that resolves this vulnerability.

    Fixed in 2.6.9
  13. Upgrade

    Upgrade RubyGems cgi gem to a version that resolves this vulnerability.

    Fixed in 0.3.1

Event History

Nov 24, 2021
CVE Published
12:00 AM
Nov 25, 2021
Data Sourced
via Red Hat·06:12 PM
DescriptionSeverityAffected Software
Jan 1, 2022
CVE Published
via MITRE·12:00 AM
Data Sourced
via MITRE·12:00 AM
Description
Data Sourced
via NVD·06:15 AM
DescriptionSeverityWeaknessAffected Software
Jan 21, 2022
Advisory Published
via GitHub·11:22 PM

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

What is CVE-2021-41819?

CVE-2021-41819 is a vulnerability in Ruby that allows remote attackers to conduct cookie prefix spoofing attacks.

2

How does CVE-2021-41819 affect RubyGems CGI gem?

CVE-2021-41819 affects the CGI gem in RubyGems, specifically the CGI::Cookie.parse function.

3

What is the severity of CVE-2021-41819?

CVE-2021-41819 has a severity rating of high.

4

How can an attacker exploit CVE-2021-41819?

An attacker can exploit CVE-2021-41819 by sending a specially-crafted request to perform cookie prefix spoofing attacks.

5

How can I fix CVE-2021-41819?

To fix CVE-2021-41819, update to the latest version of RubyGems CGI gem that includes the necessary security patches.

Company

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