CVE-2021-28834: Debian Linux

Critical severity, CVSS 9.8. EPSS: 2.8% chance of exploitation in the next 30 days.

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

Affected products

• Debian Debian Linux: version 10.0 only
• Fedoraproject Fedora: version 32 only; version 33 only; version 34 only
• Kramdown Project Kramdown: before 2.3.1 (fixed in 2.3.1)

Published 2021-03-19. Last modified 2026-06-17.