Mistune 3.3.0 before 3.3.4 Quadratic-Time DoS via _process_emphasis_delimiters

Summary

Mistune from 3.3.0 before 3.3.4 contains a denial of service vulnerability that allows remote attackers to exhaust CPU through quadratic-time emphasis delimiter processing. Attackers can submit small markdown documents with repeated patterns like "*a_b" to trigger an O(n²) index-fixup loop, stalling workers for seconds.

Remediation

1. Inventory every lepture mistune deployment, including staging.
2. Upgrade lepture mistune to 3.3.4.
3. Confirm the running version after the upgrade.

References

• Patchhttps://github.com/lepture/mistune/commit/b4dd3284e52ec741ed9a227db29ade9017828e90
• Advisoryhttps://github.com/lepture/mistune/security/advisories/GHSA-qp42-r9j6-83g9
• Advisoryhttps://www.vulncheck.com/advisories/mistune-3.3.0-before-3.3.4-quadratic-time-dos-via-process-emphasis-delimiters