---
cve: "CVE-2026-53538"
severity: "LOW"
cvss: 3.7
epss: "0.3%"
vendor: "Kludex"
kev: false
exploited: false
published: "2026-06-22 18:16:44"
tags: [cve, security, low]
source: tsecurity.de CVE-Dossier
exported: "2026-09-20T14:38:43+02:00"
---

# CVE-2026-53538

> 3.7 LOW · 🧪 PoC

## Beschreibung

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-Vektor

```
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 9d3ead568a259f222cff6425262ff63e88d930d4 (Commit)

## Referenzen

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

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-53538) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_