Bug 2390942 (CVE-2025-57804) - CVE-2025-57804 h2: h2 allows HTTP Request Smuggling due to illegal characters in headers
Summary: CVE-2025-57804 h2: h2 allows HTTP Request Smuggling due to illegal characters...
Keywords:
Status: NEW
Alias: CVE-2025-57804
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-08-25 22:01 UTC by OSIDB Bzimport
Modified: 2025-08-26 14:24 UTC (History)
44 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2025-08-25 22:01:35 UTC 
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.
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