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 redirect same-page navigation, CSS selectors, or JavaScript handlers. This issue is fixed in version 3.3.0.
{
"cwe_ids": [
"CWE-1284",
"CWE-345"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59930.json",
"cna_assigner": "GitHub_M"
}{
"cpe": "cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*",
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "3.3.0"
}
],
"source": [
"CPE_RANGE",
"REFERENCES"
]
}