DEBIAN-CVE-2026-49851
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Mistune is vulnerable to a CPU exhaustion DoS due to superlinear (approximately O(n²)) behavior in parse_link_text. When parsing Markdown containing many consecutive [ characters, parse_link_text repeatedly scans the input using a regex search inside a loop. Each iteration re-scans a large portion of the remaining string, resulting in quadratic-time behavior. An attacker-controlled Markdown input can therefore trigger excessive CPU usage with a very small payload. This vulnerability is fixed in 3.3.0.
DEBIAN-CVE-2026-49851
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:DEBIAN-CVE-2026-49851
mistune
Source reference: /affected/0/package/name
- Affected versions
- 3.1.3-1
Source reference:
/affected/0/versions3.1.4-1Source reference:
/affected/0/versions3.3.4-1Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
mistune
Source reference: /affected/1/package/name
- Affected versions
- 3.1.3-1
Source reference:
/affected/1/versions3.1.4-1Source reference:
/affected/1/versions3.3.4-1Source reference:
/affected/1/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"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"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-49851.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"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-49851.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #57193 · Revision 1
- Added to Heist Feed
- Publisher date