# CVE-2022-34749: Mistune vulnerable to catastrophic backtracking

Source: https://junglewise.ai/threats/cve-2022-34749-mistune-vulnerable-to-catastrophic-backtracking  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2022-07-25  
License: CC BY 4.0 with a link back

CVE-2022-34749 · Severity: low · CVSS 3.1 · Published 2022-07-25

In mistune through 2.0.2, support of inline markup is implemented by using regular expressions that can involve a high amount of backtracking on certain edge cases. This behavior is commonly named catastrophic backtracking.

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

## Quick answers

**Is CVE-2022-34749 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2022-34749 being exploited in the wild.

**How severe is CVE-2022-34749?** Low severity, with a CVSS score of 3.1, published 25 July 2022.

**Which products and versions are affected?** mistune (PyPI) ECOSYSTEM:introduced=2.0.0a1,fixed=2.0.3, GIT:introduced=0,fixed=a6d43215132fe4f3d93f8d7e90ba83b16a0838b2|ECOSYSTEM:introduced=2.0.0a1,fixed=2.0.3.

**Is there a fix for CVE-2022-34749?** Yes. mistune (PyPI): upgrade to 2.0.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2022-34749?** 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 2.0.3 or later

  ```sh
  pip install "mistune>=2.0.3"
  ```


## Affected products

- mistune (PyPI) ECOSYSTEM:introduced=2.0.0a1,fixed=2.0.3, GIT:introduced=0,fixed=a6d43215132fe4f3d93f8d7e90ba83b16a0838b2|ECOSYSTEM:introduced=2.0.0a1,fixed=2.0.3

## Identifiers

- CVE-2022-34749
- GHSA-fw3v-x4f2-v673
- PYSEC-2022-237

## 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)