Medium
mistune — security advisory
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.
- Products
- mistune
- Affected versions
- 0.6-2, 0.7.1-1, 0.7.4-1, 0.8-1, 0.8.1-1, 0.8.3-2, 0.8.4-1, 0.8.4-2, 0.8.4-4, 0.8.4-5, 2.0.0-1+really0.8.4-1, 2.0.4-2, 3.0.2-1, 3.0.2-2, 3.1.3-1, 3.1.4-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-59927
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 01:39 UTC · Revision 1
Source evidence
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.
osv:UBUNTU-CVE-2026-59927
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
mistune
Fixed versions: Not specified
Complete source record
{
"id": "11514be409b48274dc068d9375eaff742882b34a4fca7f025ae0c6f2d4740844",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-59927",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-59927",
"summary": "Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.",
"evidence": "osv:UBUNTU-CVE-2026-59927",
"products": [
{
"name": {
"value": "mistune",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.6-2",
"evidence": "/affected/0/versions"
},
{
"value": "0.7.1-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "mistune",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.7.4-1",
"evidence": "/affected/1/versions"
},
{
"value": "0.8-1",
"evidence": "/affected/1/versions"
},
{
"value": "0.8.1-1",
"evidence": "/affected/1/versions"
},
{
"value": "0.8.3-2",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "mistune",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.8.4-1",
"evidence": "/affected/2/versions"
},
{
"value": "0.8.4-2",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "mistune",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.8.4-4",
"evidence": "/affected/3/versions"
},
{
"value": "0.8.4-5",
"evidence": "/affected/3/versions"
},
{
"value": "2.0.0-1+really0.8.4-1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
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"evidence": "/affected/4/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
"value": "2.0.4-2",
"evidence": "/affected/4/versions"
},
{
"value": "3.0.2-1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "mistune",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.2-2",
"evidence": "/affected/5/versions"
},
{
"value": "3.1.3-1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "mistune",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.1.4-1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "mistune",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.1.3-1",
"evidence": "/affected/7/versions"
},
{
"value": "3.1.4-1",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-59927",
"aliases": [
"UBUNTU-CVE-2026-59927"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "mistune",
"purl": "pkg:deb/ubuntu/mistune?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"0.6-2",
"0.7.1-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59927.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-mistune",
"binary_version": "0.7.1-1"
},
{
"binary_name": "python3-mistune",
"binary_version": "0.7.1-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "mistune",
"purl": "pkg:deb/ubuntu/mistune?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"0.7.4-1",
"0.8-1",
"0.8.1-1",
"0.8.3-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59927.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-mistune",
"binary_version": "0.8.3-2"
},
{
"binary_name": "python3-mistune",
"binary_version": "0.8.3-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "mistune",
"purl": "pkg:deb/ubuntu/mistune?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"0.8.4-1",
"0.8.4-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59927.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-mistune",
"binary_version": "0.8.4-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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],
"package": {
"name": "mistune",
"purl": "pkg:deb/ubuntu/mistune?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"0.8.4-4",
"0.8.4-5",
"2.0.0-1+really0.8.4-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59927.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-mistune",
"binary_version": "2.0.0-1+really0.8.4-1"
}
]
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},
{
"ranges": [
{
"type": "ECOSYSTEM",
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],
"package": {
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"purl": "pkg:deb/ubuntu/mistune?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"2.0.4-2",
"3.0.2-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59927.json"
},
"ecosystem_specific": {
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}
]
}
},
{
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]
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],
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"purl": "pkg:deb/ubuntu/mistune?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"3.0.2-2",
"3.1.3-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59927.json"
},
"ecosystem_specific": {
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{
"binary_name": "python3-mistune",
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}
]
}
},
{
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],
"package": {
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"ecosystem": "Ubuntu:26.10"
},
"versions": [
"3.1.4-1"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
"binary_name": "python3-mistune",
"binary_version": "3.1.4-1"
}
]
}
},
{
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{
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"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"3.1.3-1",
"3.1.4-1"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
"binary_name": "python3-mistune",
"binary_version": "3.1.4-1"
}
]
}
}
],
"modified": "2026-10-17T12:57:17.704222379Z",
"provider": "osv",
"upstream": [
"CVE-2026-59927"
],
"references": [
"https://ubuntu.com/security/CVE-2026-59927",
"https://www.cve.org/CVERecord?id=CVE-2026-59927",
"https://github.com/lepture/mistune/security/advisories/GHSA-8mpj-m6qm-5qr8"
]
},
"related_cves": [
{
"value": "CVE-2026-59927",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 357117,
"published_at": "2026-07-08T17:17:00+00:00"
}