CVE-2025-57804
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.
- Fix
- Available
- CVSS 4.0
- 6.9 MEDIUM
- EPSS
- 1.7% (75th percentile)
- Weakness
- CWE-93
- NVD status
- Deferred
- Published
- 2025-08-25
CVE-2025-57804 at NVD
No indexed exploits for CVE-2025-57804 yet
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No exploit for CVE-2025-57804 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.