inline_parser: quadratic-time parsing on long runs of `**x**` and `***x***` emphasis pairs (lepture mistune)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.64 % · percentile 51 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
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.
Weaknesses (CWE)
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-4j32-57v6-6g45 — Mistune inline_parser: quadratic-time parsing on long runs of `**x**` and `***x***` emphasis pairs
- PYSEC-2026-2213 — 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
European references
- ENISA EUVD · EUVD-2026-42335
- GCVE · GCVE-0-2026-59925
Affected configurations (NVD CPE)
cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*< 3.3.0
Affected products
| Product | Versions |
|---|---|
| lepture · mistune | affected < 3.3.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |