TI-2026-38610 Aliases CVE-2026-53537 GHSA-vffw-93wf-4j4q

Python-Multipart: Content-Disposition parameter smuggling via RFC 2231/5987 extended parameters

LOW 24CWE-20Published 2026-06-22 · Updated 2026-06-23

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: None · Low · None
Fix status: Partial Red Hat: 9 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA, GitHub and Red Hat.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00291 21st percentileScored 2026-11-07

Fix Partial python-multipart (Kludex): 0.0.30python-multipart (PyPI): 0.0.30Red Hat: 9 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Kludex	python-multipart	before 0.0.30	0.0.30	Patch available	CNA
—	python-multipart (PyPI)	before 0.0.30	0.0.30	Patch available	GHSA-vffw-93wf-4j4q

python-multipart VendorKludex Affected before 0.0.30 Fixed in 0.0.30 Patch available CNA
python-multipart (PyPI) Vendor— Affected before 0.0.30 Fixed in 0.0.30 Patch available GHSA-vffw-93wf-4j4q

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:fastapiexpert:python-multipart::::::python::*	before 0.0.30	Vulnerable	Fastapiexpert

cpe:2.3:a:fastapiexpert:python-multipart:*:*:*:*:*:python:*:* Versions before 0.0.30 Vulnerable ·Fastapiexpert

Remediation

Fix · CNA python-multipart (Kludex) Fixed in 0.0.30
Fix · GHSA-vffw-93wf-4j4q python-multipart (PyPI) Fixed in 0.0.30 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

Product	Status	Plan or fix
Exploit Intelligence	Affected	No fix yet: Fix deferred
Migration Toolkit for Applications 8	Affected	No fix yet: Fix deferred
OpenShift Lightspeed	Affected	No fix yet: Fix deferred
Red Hat AI Inference Server	Affected	No fix yet: Fix deferred
Red Hat Ansible Automation Platform 2	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux AI (RHEL AI) 3	Affected	No fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)	Affected	No fix yet: Fix deferred
Red Hat OpenShift Virtualization 4	Affected	No fix yet: Fix deferred
Red Hat Satellite 6	Affected	No fix yet: Fix deferred

Not affected: 3 products

Lightspeed Core
Red Hat Enterprise Linux command line assistant
Red Hat Hardened Images

Timeline

2026-10-02 Threatist record created from CVE-2026-53537
2026-10-03 Alias added: GHSA-vffw-93wf-4j4q

References

Advisory 3

Other 3

TI-2025-38917 Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse CVSS 3.1HIGH 7.5
TI-2026-30841 Python-Multipart: Denial of Service via unbounded multipart part headers CVSS 3.1HIGH 7.5
TI-2024-36140 python-multipart has a Denial of service (DoS) via deformation `multipart/form-data` boundary CVSS 3.1HIGH 7.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences