CVE-2026-59930

EUVD-2026-42330
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
4.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 3.71%
Affected Products (NVD)
VendorProductVersion
mistune_projectmistune
𝑥
< 3.3.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
mistune
bookworm
postponed
bullseye
0.8.4-4
fixed
forky
vulnerable
sid
vulnerable
trixie
no-dsa
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
mistune
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
questing
ignored
resolute
needs-triage
Azure Linux logo
Azure Linux Releases
Azure Package
Release
python-mistune
Azure Linux 3.0
0:3.3.0-1.azl3
fixed
Common Weakness Enumeration
References
https://github.com/lepture/mistune/commit/c4093c4742ed0d10d9332fb8edb455869b7b581b
https://github.com/lepture/mistune/releases/tag/v3.3.0
https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9
https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9