Vulnerability in Lepture Mistune
CVE-2026-59930
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.
EPSS: 0.001 (3.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N.
Affected products
- Lepture Mistune — versions < 3.3.0
- Mistune_project Mistune
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Third Party Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-59930?
- CVE-2026-59930 is a medium-severity vulnerability in Lepture Mistune, classified under Insufficient Verification of Data Authenticity. CVSS score: 4.3/10. Published 2026-07-08.
- How severe is CVE-2026-59930?
- Medium severity. CVSS v3 base score is 4.3 out of 10.