High severity7.5OSV Advisory· Published Jul 8, 2026· Updated Jul 9, 2026
CVE-2026-59925
CVE-2026-59925
Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, long sequences of well-formed double-asterisk or triple-asterisk emphasis pairs around a character cause quadratic work in src/mistune/inline_parser.py because the parser scans forward for matching close markers from every potential opening run, allowing denial of service in default Mistune parsing. This issue is fixed in version 3.3.0.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
mistunePyPI | < 3.3.0 | 3.3.0 |
Affected products
4Patches
Vulnerability mechanics
References
6- github.com/lepture/mistune/commit/5de41fb8e527004dbc363e047a3c380c9288c74fnvdPatchWEB
- github.com/lepture/mistune/security/advisories/GHSA-4j32-57v6-6g45nvdExploitVendor AdvisoryWEB
- github.com/advisories/GHSA-4j32-57v6-6g45ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-59925ghsaADVISORY
- github.com/lepture/mistune/releases/tag/v3.3.0nvdRelease NotesWEB
- github.com/pypa/advisory-database/tree/main/vulns/mistune/PYSEC-2026-2213.yamlghsaWEB
News mentions
2- Mistune Project: Nine Vulnerabilities Including DoS and XSS Disclosed TogetherVypr Intelligence · Jul 9, 2026
- Authlib Mistune: Nine Vulnerabilities Including DoS and XSS Disclosed TogetherVypr Intelligence · Jul 9, 2026