CVE-2026-53537 (GCVE-0-2026-53537)
Vulnerability from cvelistv5 – Published: 2026-06-22 16:57 – Updated: 2026-06-23 16:08
VLAI
EPSS
VEX
Title
Python-Multipart: Content-Disposition parameter smuggling via RFC 2231/5987 extended parameters
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.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-23 16:03 UTC
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/Kludex/python-multipart/securi… | x_refsource_CONFIRM |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Kludex | python-multipart |
Affected:
< 0.0.30
|
guessed |
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