---
cve: "CVE-2025-57804"
severity: "MEDIUM"
cvss: 6.9
epss: "1.7%"
vendor: "python-hyper"
kev: false
exploited: false
published: "2025-08-25 21:15:37"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-26T06:16:11+02:00"
---

# CVE-2025-57804

> 6.9 MEDIUM · 🧪 PoC

## Beschreibung

h2 is a pure-Python implementation of a HTTP/2 protocol stack. Prior to version 4.3.0, an HTTP/2 request splitting vulnerability allows attackers to perform request smuggling attacks by injecting CRLF characters into headers. This occurs when servers downgrade HTTP/2 requests to HTTP/1.1 without properly validating header names/values, enabling attackers to manipulate request boundaries and bypass security controls. This issue has been patched in version 4.3.0.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 035e9899f95e3709af098f578bfc3cd302298e3a (Commit)

## Referenzen

- <https://github.com/python-hyper/h2/security/advisories/GHSA-847f-9342-265h>
- <https://github.com/python-hyper/h2/commit/035e9899f95e3709af098f578bfc3cd302298e3a>
- <https://lists.debian.org/debian-lts-announce/2025/09/msg00004.html>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2025-57804) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_