High
mistune — security advisory
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. 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-2026-59922
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:48 UTC · Revision 1
Source evidence
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
osv:UBUNTU-CVE-2026-59922
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": "1078c0dd0f10f419fb0baa4d106e873e10c25b578ef512136c50f5fab8e11fd4",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-59922",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-59922",
"summary": "Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.",
"evidence": "osv:UBUNTU-CVE-2026-59922",
"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": {
"value": "mistune",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"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": "high",
"structured": {
"id": "UBUNTU-CVE-2026-59922",
"aliases": [
"UBUNTU-CVE-2026-59922"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
"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-2026-59922.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-2026-59922.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-2026-59922.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-2026-59922.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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}
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],
"package": {
"name": "mistune",
"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-2026-59922.json"
},
"ecosystem_specific": {
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}
]
}
},
{
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]
}
],
"package": {
"name": "mistune",
"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-2026-59922.json"
},
"ecosystem_specific": {
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{
"binary_name": "python3-mistune",
"binary_version": "3.1.3-1"
}
]
}
},
{
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}
],
"package": {
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"purl": "pkg:deb/ubuntu/mistune?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"3.1.4-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59922.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-mistune",
"binary_version": "3.1.4-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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}
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],
"package": {
"name": "mistune",
"purl": "pkg:deb/ubuntu/mistune?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"3.1.3-1",
"3.1.4-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59922.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-mistune",
"binary_version": "3.1.4-1"
}
]
}
}
],
"modified": "2026-10-17T12:59:14.309375667Z",
"provider": "osv",
"upstream": [
"CVE-2026-59922"
],
"references": [
"https://ubuntu.com/security/CVE-2026-59922",
"https://www.cve.org/CVERecord?id=CVE-2026-59922",
"https://github.com/lepture/mistune/security/advisories/GHSA-c8j7-8cv4-2xmq"
]
},
"related_cves": [
{
"value": "CVE-2026-59922",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359514,
"published_at": "2026-07-08T17:17:00+00:00"
}