Medium
mistune — security advisory
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safe_url() does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version 3.3.0.
- Products
- mistune
- Affected versions
- 2.0.4-1, 2.0.4-2, 3.0.2-1, 3.0.2-2, 3.1.3-1, 3.1.4-1, 3.3.4-1, 3.4.0-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-59923
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 13:35 UTC · Revision 2
Source evidence
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safe_url() does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version 3.3.0.
osv:DEBIAN-CVE-2026-59923
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
Complete source record
{
"id": "0919b847877ced32d56edcd246e8c179cace550560229f817fbebc37bcf251ca",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-59923",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-59923",
"summary": "Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safe_url() does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version 3.3.0.",
"evidence": "osv:DEBIAN-CVE-2026-59923",
"products": [
{
"name": {
"value": "mistune",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.0.4-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.0.4-2",
"evidence": "/affected/0/versions"
},
{
"value": "3.0.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "3.0.2-2",
"evidence": "/affected/0/versions"
},
{
"value": "3.1.3-1",
"evidence": "/affected/0/versions"
},
{
"value": "3.1.4-1",
"evidence": "/affected/0/versions"
},
{
"value": "3.3.4-1",
"evidence": "/affected/0/versions"
},
{
"value": "3.4.0-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "mistune",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.1.3-1",
"evidence": "/affected/1/versions"
},
{
"value": "3.1.4-1",
"evidence": "/affected/1/versions"
},
{
"value": "3.3.4-1",
"evidence": "/affected/1/versions"
},
{
"value": "3.4.0-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "mistune",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.1.3-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.4-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.3.4-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.4.0-1",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2026-59923",
"aliases": [
"DEBIAN-CVE-2026-59923"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "mistune",
"purl": "pkg:deb/debian/mistune?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"2.0.4-1",
"2.0.4-2",
"3.0.2-1",
"3.0.2-2",
"3.1.3-1",
"3.1.4-1",
"3.3.4-1",
"3.4.0-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-59923.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "mistune",
"purl": "pkg:deb/debian/mistune?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"3.1.3-1",
"3.1.4-1",
"3.3.4-1",
"3.4.0-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-59923.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "mistune",
"purl": "pkg:deb/debian/mistune?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"3.1.3-1",
"3.1.4-1",
"3.3.4-1",
"3.4.0-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-59923.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-26T12:02:35.883601699Z",
"provider": "osv",
"upstream": [
"CVE-2026-59923"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-59923"
]
},
"related_cves": [
{
"value": "CVE-2026-59923",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 452584,
"published_at": "2026-07-08T17:17:27.91+00:00"
}