Home/CVE/Kramdown before 2.3.1 does not restrict Rouge formatters to the Rouge::Formatters namespace, and thus arbitrary classes
CVE

CVE-2021-28834

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

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

CRITICAL · CVSS 9.8 EPSS 0.0259
Act now
  • Public exploit or PoC is available
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
▤

Affected Products & Versions

3
kramdown project kramdown< 2.3.1
fedoraproject fedoraall versions
debian linuxall versions
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
RubyGems kramdown HIGH fixed in 2.3.1
⚠

Public Exploits & PoCs

1
pocgithub.com · pull/708github.com
▣

Scoring & Timeline

9.8
CRITICAL · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD19 Mar 2021 · 07:15 AM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
⚑

Vendor Advisories

7
suse-csafopenSUSE-SU-2026:10352-1
suse-csafopenSUSE-SU-2025:15119-1
suse-csafopenSUSE-SU-2024:14170-1
suse-csafopenSUSE-SU-2024:11336-1
suse-csafopenSUSE-SU-2024:12038-1
🔗

References & Sources

6
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/gettalong/kramdown/compare/REL_2_3_0...REL_2_3_1PatchThird Party Advisory
https://gitlab.com/gitlab-org/gitlab/-/commit/179329b5c3c118924fb242dc449d06b4ed6ccb66PatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NJCJVYHPY6LNUFM6LYZIAUIYOMVT5QGV/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/S3BBLUIDCUUR3NEE4NJLOCCAV3ALQ3O6/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SYOLQKFL6IJCQLBXV34Z4TI4O54GESPR/
https://www.debian.org/security/2021/dsa-4890Third Party Advisory
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