CVE-2026-53538
LOW EPSS 7.3%
Published Jun 22, 20261w ago · Modified Jun 23, 20261w ago
3.7 CVSS 3.1
Published Jun 22, 2026 1w ago
Last Modified Jun 23, 2026 1w ago
Description
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.
CVSS Details
Base Score
Exploitability
Impact
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity Low
Availability None
Threat Intelligence
EPSS Exploit Probability
7.3% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available
Weaknesses 2
CWE-436
CWE-444
References 1
- github.com https://github.com/Kludex/python-multipart/security/advisories/GHSA-6jv3-5f52-599m
Remediation
No remediation data recorded yet
Check vendor advisories and the NVD entry for patch availability.