AIKIDO-2026-531832
markdown-it is vulnerable to Uncontrolled Resource Consumption
42
Medium Risk
This Affects:
markdown-itTL;DR
markdown-it exposes two quadratic complexity code paths when the non-default linkify option is enabled. Rendering markdown that contains many schema-less emails or unregistered URL schemes causes repeated array rebuilds and regex scans over ever-growing string buffers, so processing time grows with the square of the input size. Crafted markdown can pin a CPU core and block the event loop, denying service to concurrent work. The fix replaces the unbounded scheme scan with a bounded backward scan and removes the quadratic array handling.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and you have enabled the linkify option to render untrusted markdown input.
Background info
markdown-it is vulnerable to Uncontrolled Resource Consumption in versions 0.0.1 - 14.3.0 and 15.0.0 - 15.0.0.
How to fix this
Upgrade the markdown-it library to the patch version.
Are You Affected?
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