# Duplicate Advisory: Mistune has a ReDoS in LINK_TITLE_RE that allows denial of service via crafted Markdown input

Source: https://junglewise.ai/threats/duplicate-advisory-mistune-has-a-redos-in-link-title-re-that-allows-291d431c  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-06  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 4 · Published 2026-05-06

Duplicate Advisory: Mistune has a ReDoS in LINK_TITLE_RE that allows denial of service via crafted Markdown input

Technologies: [mistune (PyPI)](https://junglewise.ai/threats/technologies/mistune). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 4, published 6 May 2026.

**Which products and versions are affected?** mistune (PyPI) ECOSYSTEM:introduced=3.0.0a1,fixed=3.2.1.

**Is there a fix for This vulnerability?** Yes. mistune (PyPI): upgrade to 3.2.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected?** Check whether you run mistune (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- mistune (PyPI): upgrade to 3.2.1 or later

  ```sh
  pip install "mistune>=3.2.1"
  ```


## Affected products

- mistune (PyPI) ECOSYSTEM:introduced=3.0.0a1,fixed=3.2.1

## Related threats

- [Mistune path traversal and XSS in Include directive](https://junglewise.ai/threats/duplicate-advisory-mistune-path-traversal-and-xss-in-include-directive-bf25c187)
- [Mistune path traversal and XSS in Include directive](https://junglewise.ai/threats/cve-2026-115355-mistune-before-3-3-0-contains-a-path-traversal-vulnerability-in)
- [Mistune uncontrolled recursion in HTML rendering](https://junglewise.ai/threats/cve-2026-76098-mistune-uncontrolled-recursion-in-html-rendering)
- [lepture Mistune predictable ID generation in TOC plugin](https://junglewise.ai/threats/cve-2026-59930-lepture-mistune-predictable-id-generation-in-toc-plugin)
- [lepture mistune XSS via incomplete URL scheme filtering in HTML renderer](https://junglewise.ai/threats/cve-2026-59929-lepture-mistune-xss-via-incomplete-url-scheme-filtering-in-html)