Parsedown Class-Name Injection
Date: 2022-03
Affected: composer/erusev/parsedown
Attack vector: xss
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2019-10905
CWE: CWE-79
CVSS: 8.1 (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)

Parsedown before 1.7.2, when safe mode is used and HTML markup is disabled, might allow attackers to execute arbitrary JavaScript code if a script (already running on the affected page) executes the contents of any element with a specific class. This occurs because spaces are permitted in code block infostrings, which interferes with the intended behavior of a single class name beginning with the language- substring.


Mitigations:

Architectural layers (MAESTRO):