DEBIAN-CVE-2026-53539
Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, when parsing application/x-www-form-urlencoded bodies, QuerystringParser located the field separator with a two step lookup: it first scanned the entire remaining buffer for &, and only when no & existed anywhere ahead did it fall back to scanning for ;. For a body that uses ; as the separator and contains no &, every field iteration performed a full failed & scan over the entire remaining buffer before locating the nearby ;. With N semicolon separated fields in a chunk of size B, this yields O(B^2) byte comparisons per chunk. An attacker can submit a small crafted body of the form a;a;a;... and cause the parser to spend seconds of CPU per request. A handful of concurrent requests can exhaust worker processes. This vulnerability is fixed in 0.0.30.
DEBIAN-CVE-2026-53539
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-2026-53539
python-multipart
Source reference: /affected/0/package/name
- Affected versions
- 0.0.17-1
Source reference:
/affected/0/versions0.0.17-2Source reference:
/affected/0/versions0.0.17-3Source reference:
/affected/0/versions0.0.17-4Source reference:
/affected/0/versions0.0.17-5Source reference:
/affected/0/versions0.0.20-1Source reference:
/affected/0/versions0.0.20-1.1Source reference:
/affected/0/versions0.0.20-1.1~deb13u1Source reference:
/affected/0/versions0.0.22-1Source reference:
/affected/0/versions0.0.26-1Source reference:
/affected/0/versions0.0.32-1Source reference:
/affected/0/versions0.0.5-3Source reference:
/affected/0/versions0.0.6-1Source reference:
/affected/0/versions0.0.9-1Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
python-multipart
Source reference: /affected/1/package/name
- Affected versions
- 0.0.20-1
Source reference:
/affected/1/versions0.0.20-1.1Source reference:
/affected/1/versions0.0.20-1.1~deb13u1Source reference:
/affected/1/versions0.0.22-1Source reference:
/affected/1/versions0.0.26-1Source reference:
/affected/1/versions0.0.32-1Source reference:
/affected/1/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
python-multipart
Source reference: /affected/2/package/name
- Affected versions
- 0.0.20-1
Source reference:
/affected/2/versions0.0.20-1.1Source reference:
/affected/2/versions0.0.20-1.1~deb13u1Source reference:
/affected/2/versions0.0.22-1Source reference:
/affected/2/versions0.0.26-1Source reference:
/affected/2/versions - Fixed versions
- 0.0.32-1
Source reference:
/affected/2/ranges - 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": "python-multipart",
"purl": "pkg:deb/debian/python-multipart?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"0.0.17-1",
"0.0.17-2",
"0.0.17-3",
"0.0.17-4",
"0.0.17-5",
"0.0.20-1",
"0.0.20-1.1",
"0.0.20-1.1~deb13u1",
"0.0.22-1",
"0.0.26-1",
"0.0.32-1",
"0.0.5-3",
"0.0.6-1",
"0.0.9-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53539.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "python-multipart",
"purl": "pkg:deb/debian/python-multipart?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"0.0.20-1",
"0.0.20-1.1",
"0.0.20-1.1~deb13u1",
"0.0.22-1",
"0.0.26-1",
"0.0.32-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53539.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.0.32-1"
}
]
}
],
"package": {
"name": "python-multipart",
"purl": "pkg:deb/debian/python-multipart?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"0.0.20-1",
"0.0.20-1.1",
"0.0.20-1.1~deb13u1",
"0.0.22-1",
"0.0.26-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53539.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]- Related CVEs
- CVE-2026-53539
Source reference:
/upstream
Publisher severity
high
Source reference: /severity/0/score
- Event
- #81910 · Revision 1
- Added to Heist Feed
- Publisher date