CVE-2025-57804
Published: Aug 25, 2025
Modified: Nov 3, 2025
Description
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.
| Vendor | Product | Versions |
|---|---|---|
python-hyper | h2 | affected < 4.3.0 |
Weaknesses (CWE)
References
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