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.
CVE-2026-59925
This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 72% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EPSS
- 27.9%
- KEV
- Not listed
Published
July 8, 2026
Last Modified
July 9, 2026
Advisory Details (3)
Auto-updated Jul 8, 2026inline_parser: quadratic-time parsing on long runs of `**x**` and `***x***` emphasis pairs · Advisory · lepture/mistune · GitHub
https://github.com/lepture/mistune/security/advisories/GHSA-4j32-57v6-6g45v3.3.0
Patch available: lepture/mistune v3.3.0
https://github.com/lepture/mistune/releases/tag/v3.3.0commit 5de41fb8e527 (lepture/mistune)
Patch available: lepture/mistune v3.3.0 (contains commit 5de41fb8e527)
https://github.com/lepture/mistune/commit/5de41fb8e527004dbc363e047a3c380c9288c74fVendor Advisories for CVE-2026-59925(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 12× in last 7d / 12× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-11 20:17 UTCEG score recompute
- 2026-07-11 08:27 UTCEPSS rescore
- 2026-07-11 08:27 UTCEPSS rescore
- 2026-07-11 07:37 UTCEG score recompute
- 2026-07-10 18:59 UTCEG score recompute
- 2026-07-10 06:20 UTCEG score recompute
- 2026-07-09 19:10 UTCEPSS rescore
- 2026-07-09 19:10 UTCEPSS rescore
- 2026-07-09 17:42 UTCEG score recompute
- 2026-07-09 05:03 UTCEG score recompute
- 2026-07-08 16:24 UTCEG score recompute
- 2026-07-08 16:24 UTCMITRE cvelistV5first tracked
Frequently asked(5)
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Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-59925
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