critical
9.8
Advisory Published
CVE Published
Updated

CVE-2021-28834

First published: Fri Mar 19 2021(Updated: )

Kramdown before 2.3.1 does not restrict Rouge formatters to the Rouge::Formatters namespace, and thus arbitrary classes can be instantiated.

Credit: cve@mitre.org cve@mitre.org

Affected SoftwareAffected VersionHow to fix
ubuntu/ruby-kramdown<1.17.0-4ubuntu0.2
1.17.0-4ubuntu0.2
ubuntu/ruby-kramdown<2.3.1
2.3.1
<2.3.1
=32
=33
=34
=10.0
Kramdown Project Kramdown<2.3.1
Fedoraproject Fedora=32
Fedoraproject Fedora=33
Fedoraproject Fedora=34
Debian Debian Linux=10.0
redhat/rubygem-kramdown<2.3.1
2.3.1
debian/ruby-kramdown
1.17.0-1+deb10u2
2.3.0-5
2.4.0-2

Remedy

https://github.com/gettalong/kramdown/compare/REL_2_3_0...REL_2_3_1

Remedy

https://gitlab.com/gitlab-org/gitlab/-/commit/179329b5c3c118924fb242dc449d06b4ed6ccb66

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Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Frequently Asked Questions

  • What is the severity of CVE-2021-28834?

    The severity of CVE-2021-28834 is medium.

  • Which software is affected by CVE-2021-28834?

    The software affected by CVE-2021-28834 is ruby-kramdown version 1.17.0-1+deb10u2, 2.3.0-5, 2.4.0-2, and rubygem-kramdown version up to 2.3.1.

  • How can arbitrary classes be instantiated in Kramdown before version 2.3.1?

    Kramdown before version 2.3.1 does not restrict Rouge formatters to the Rouge::Formatters namespace, allowing arbitrary classes to be instantiated.

  • What is the fix for CVE-2021-28834?

    To fix CVE-2021-28834, update to kramdown version 2.3.1 or higher.

  • Where can I find more information about CVE-2021-28834?

    More information about CVE-2021-28834 can be found on the [CVE website](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-28834) and on the [GitHub page](https://github.com/gettalong/kramdown/pull/708).

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