UBUNTU-CVE-2026-53539

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Source
https://ubuntu.com/security/CVE-2026-53539
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53539.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-53539
Upstream
Published
2026-06-22T18:16:00Z
Modified
2026-06-24T11:01:52.241261007Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

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.

References

Affected packages

Ubuntu:Pro:22.04:LTS / python-multipart

Package

Name
python-multipart
Purl
pkg:deb/ubuntu/python-multipart?arch=source&distro=esm-apps%2Fjammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.0.5-2
0.0.5-2ubuntu0.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-multipart",
            "binary_version": "0.0.5-2ubuntu0.1~esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53539.json"

Ubuntu:Pro:24.04:LTS / python-multipart

Package

Name
python-multipart
Purl
pkg:deb/ubuntu/python-multipart?arch=source&distro=esm-apps%2Fnoble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.0.5-3
0.0.6-1
0.0.9-1
0.0.9-1ubuntu0.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-multipart",
            "binary_version": "0.0.9-1ubuntu0.1~esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53539.json"

Ubuntu:25.10 / python-multipart

Package

Name
python-multipart
Purl
pkg:deb/ubuntu/python-multipart?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.0.20-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-python-multipart",
            "binary_version": "0.0.20-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53539.json"

Ubuntu:26.04:LTS / python-multipart

Package

Name
python-multipart
Purl
pkg:deb/ubuntu/python-multipart?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.0.20-1
0.0.20-1.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-python-multipart",
            "binary_version": "0.0.20-1.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53539.json"