3.7

CVE-2026-53538

Python-Multipart: Semicolon treated as querystring field separator enables parameter smuggling

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, QuerystringParser treated ; as a field separator in application/x-www-form-urlencoded bodies, in addition to &. The WHATWG URL standard, modern browsers, and Python's urllib.parse (since the CVE-2021-23336 fix) treat only & as a separator. This creates a parser differential: the same bytes are tokenized into different fields than a WHATWG compliant intermediary would produce, allowing an attacker to smuggle extra form fields past an upstream body inspecting component. This vulnerability is fixed in 0.0.30.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
FastapiexpertPython-multipart SwPlatformpython Version < 0.0.30
Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.18% 0.072
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
security-advisories@github.com 3.7 2.2 1.4
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE-436 Interpretation Conflict

Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.

CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

https://github.com/Kludex/python-multipart/security/advisories/GHSA-6jv3-5f52-599m
Vendor Advisory