Markdown-It Project: >> Markdown-It >> 4.0.3 Security Vulnerabilities
markdown-it is a Markdown parser. Versions 14.1.1 and below contain a denial-of-service vulnerability when typographer: true is enabled, due to quadratic (O(n^2)) processing in the smartquotes rule. The issue stems from repeatedly modifying strings with replaceAt(), which performs O(n) slicing and concatenation per quote character. This can cause excessive CPU consumption when parsing quote-heavy, user-supplied markdown and may let attackers degrade or disrupt service availability. Although typographer is disabled by default, many production apps enable it for smart typography, making the issue relevant. This issue has been fixed in version 14.2.0.
CVSS Score
5.3
EPSS Score
0.003
Published
2026-06-17
markdown-it is a Markdown parser. Prior to version 1.3.2, special patterns with length greater than 50 thousand characterss could slow down the parser significantly. Users should upgrade to version 12.3.2 to receive a patch. There are no known workarounds aside from upgrading.
CVSS Score
5.3
EPSS Score
0.022
Published
2022-01-10
markdown-it before 4.1.0 does not block data: URLs.
CVSS Score
5.3
EPSS Score
0.013
Published
2017-06-07