CVE intelligence and bounded remediation
CVE-2026-59930 — Mistune is a Python Markdown parser with renderers and plugins
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.
- Severity
- Medium
- CVSS
- 4.3 (3.1)
- Published
- 2026-07-08
- CISA KEV
- Not currently listed
- Ecosystem
- javascript/npm
- Weaknesses
- CWE-345, CWE-1284
Affected products
- mistune_project / mistune
Matched remediation archetype
Supply-chain, dependency, build, and update integrity
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Trace affected packages, source archives, build actions, plugins, installers, and updates from declared source to deployed artifact.
- Confirm provenance, signatures or digests, namespace ownership, lockfile resolution, registry configuration, and build-runner trust boundaries.
- Inventory direct, transitive, vendored, generated, and bundled copies across releases and distribution channels.
Remediate safely
- Move to a maintained trusted artifact or remove the dependency; pin immutable identities and verify provenance and integrity before use.
- Regenerate lockfiles and artifacts in a clean isolated build, minimize build credentials and network access, and produce an updated software bill of materials.
- Require reviewed update policy, protected publishing, and reproducible or independently attestable builds where supported.
Authoritative sources
Complete CVE record and remediation plan
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