CVE-2026-53538
LOW
3.7
CVSS 3.1
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.
Metadata
Severity & Metrics
3.7
LOW CVSS 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Affected products (1)
| Vendor | Product | Platform | Versions |
|---|---|---|---|
| Kludex | python-multipart | — | < 0.0.30 |
Weakness (CWE)
CVSS scores (1)
| Score | Severity | Version | Source | Vector |
|---|---|---|---|---|
| 3.7 | LOW | 3.1 | cna | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |
References (1)
- https://github.com/Kludex/python-multipart/security/advisories/GHSA-6jv3-5f52-599m https://github.com/Kludex/python-multipart/security/advisories/GHSA-6jv3-5f52-599m