CVE-2026-59930 | THREATINT

Description

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.

PUBLISHED Reserved 2026-07-07 | Published 2026-07-08 | Updated 2026-07-09 | Assigner GitHub_M

MEDIUM: 4.3CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Problem types

CWE-345: Insufficient Verification of Data Authenticity

CWE-1284: Improper Validation of Specified Quantity in Input

Product status

< 3.3.0

affected

References

github.com/...istune/security/advisories/GHSA-2hm2-hc3v-44h9 exploit

github.com/...istune/security/advisories/GHSA-2hm2-hc3v-44h9

github.com/...ommit/c4093c4742ed0d10d9332fb8edb455869b7b581b

github.com/lepture/mistune/releases/tag/v3.3.0

cve.org (CVE-2026-59930)

nvd.nist.gov (CVE-2026-59930)

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