Description
Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, parse_options_header parsed Content-Disposition (and Content-Type) headers with email.message.Message, which transparently applies RFC 2231/5987 decoding. The extended parameter syntax (filename*=charset'lang'value, name*=..., and the filename*0/filename*1 continuation form) is decoded and surfaced under the bare filename/name key, and overrides the plain parameter when both are present. RFC 7578 §4.2 explicitly forbids the filename* form in multipart/form-data. Components that follow RFC 7578, or that do not implement RFC 2231/5987 decoding for multipart/form-data (WAFs, proxies, gateways), may interpret such a header differently. An attacker can exploit that difference to smuggle a different field name or filename past an upstream inspector to the backend. This vulnerability is fixed in 0.0.30.
Published: 2026-06-22
Score: 3.7 Low
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Github GHSA Github GHSA GHSA-vffw-93wf-4j4q python-multipart: Content-Disposition parameter smuggling via RFC 2231/5987 extended parameters
History

Tue, 30 Jun 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-1286
References
Metrics threat_severity

None

threat_severity

Low


Tue, 23 Jun 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 22 Jun 2026 20:15:00 +0000

Type Values Removed Values Added
First Time appeared Kludex
Kludex python-multipart
Vendors & Products Kludex
Kludex python-multipart

Mon, 22 Jun 2026 17:30:00 +0000

Type Values Removed Values Added
Description Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, parse_options_header parsed Content-Disposition (and Content-Type) headers with email.message.Message, which transparently applies RFC 2231/5987 decoding. The extended parameter syntax (filename*=charset'lang'value, name*=..., and the filename*0/filename*1 continuation form) is decoded and surfaced under the bare filename/name key, and overrides the plain parameter when both are present. RFC 7578 §4.2 explicitly forbids the filename* form in multipart/form-data. Components that follow RFC 7578, or that do not implement RFC 2231/5987 decoding for multipart/form-data (WAFs, proxies, gateways), may interpret such a header differently. An attacker can exploit that difference to smuggle a different field name or filename past an upstream inspector to the backend. This vulnerability is fixed in 0.0.30.
Title Python-Multipart: Content-Disposition parameter smuggling via RFC 2231/5987 extended parameters
Weaknesses CWE-20
CWE-436
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}


Subscriptions

Kludex Python-multipart
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-23T16:08:07.690Z

Reserved: 2026-06-09T18:13:07.262Z

Link: CVE-2026-53537

cve-icon Vulnrichment

Updated: 2026-06-23T16:03:19.747Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Low

Publid Date: 2026-06-22T16:57:21Z

Links: CVE-2026-53537 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-06-30T14:00:06Z

Weaknesses