CVE-2026-59930

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 97% 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).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this weekElevated
4.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the toc plugin and TableOfContents directive generate heading IDs as predictable toc_N values without slugifying the heading text, allowing attacker-controlled id="toc_N" content to collide with generated anchors and redirect same-page navigation, CSS selectors, or JavaScript handlers. This issue is fixed in version 3.3.0.

CVSS v3
4.3
EG Score
4.3(medium)
EPSS
2.8%
KEV
Not listed

Published

July 8, 2026

Last Modified

July 9, 2026

Advisory Details (3)

Auto-updated Jul 9, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github_release Patch Available

v3.3.0

Patch available: lepture/mistune v3.3.0

https://github.com/lepture/mistune/releases/tag/v3.3.0
github_commit Patch Available

commit c4093c4742ed (lepture/mistune)

Patch available: lepture/mistune v3.3.0 (contains commit c4093c4742ed)

https://github.com/lepture/mistune/commit/c4093c4742ed0d10d9332fb8edb455869b7b581b
github Patch Available🟡 PoC Available

toc / TableOfContents directive: heading IDs use predictable `toc_N` numbering with no slugification, allowing collision with attacker-controlled `id="toc_N"` content · Advisory · lepture/mistune · GitHub

https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9

Vendor Advisories for CVE-2026-59930(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 9× in last 7d / 9× 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.

  1. 2026-07-11 14:09 UTCEG score recompute
  2. 2026-07-11 08:27 UTCEPSS rescore
  3. 2026-07-11 08:27 UTCEPSS rescore
  4. 2026-07-10 14:54 UTCEG score recompute
  5. 2026-07-09 19:10 UTCEPSS rescore
  6. 2026-07-09 19:10 UTCEPSS rescore
  7. 2026-07-09 15:40 UTCEG score recompute
  8. 2026-07-08 16:24 UTCEG score recompute
  9. 2026-07-08 16:24 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-59930?
CVE-2026-59930 is a medium vulnerability published on July 8, 2026. Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the toc plugin and TableOfContents directive generate heading IDs as predictable tocN values without slugifying the heading text, allowing attacker-controlled id="tocN" content to collide with generated anchors and…
When was CVE-2026-59930 disclosed?
CVE-2026-59930 was first published in the National Vulnerability Database on July 8, 2026, with the most recent update on July 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59930 actively exploited?
CVE-2026-59930 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-59930?
CVE-2026-59930 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-59930?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59930, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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