CVE-2025-57804 (GCVE-0-2025-57804)
Vulnerability from cvelistv5
Published
2025-08-25 21:04
Modified
2025-11-03 18:13
Severity ?
6.9 (Medium) - 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
CWE
  • CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
Summary
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.
References
Impacted products
Vendor Product Version
python-hyper h2 Version: < 4.3.0
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