CVE-2019-10905

Severity: high (CVSS 8.1 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2019-04-06 · updated 2026-06-17
Weakness: CWE-79

Description

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.

Affected products

Parsedown: before 1.7.2 — fixed in 1.7.2

How to fix

Upgrade to a fixed version: Parsedown 1.7.2. Check the vendor advisory for mitigations.

References

https://github.com/erusev/parsedown/issues/699
https://github.com/erusev/parsedown/releases/tag/1.7.2
https://github.com/erusev/parsedown/issues/699
https://github.com/erusev/parsedown/releases/tag/1.7.2

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