Bug 2390942 (CVE-2025-57804)

Summary: CVE-2025-57804 h2: h2 allows HTTP Request Smuggling due to illegal characters in headers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: adudiak, bkabrda, dbosanac, dhanak, drosa, dsimansk, gotiwari, haoli, hkataria, jajackso, jcammara, jcantril, jmitchel, jneedle, jreimann, jwendell, kegrant, kingland, koliveir, kshier, kverlaen, lball, mabashia, matzew, mdessi, mnovotny, mrizzi, mvyas, ngough, pbraun, pcattana, rcernich, rojacob, sausingh, sdawley, shvarugh, simaishi, smcdonal, stcannon, teagle, tfister, thavo, veshanka, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A vulnerability was found in python-hyper/h2 that contains an input validation flaw that allows carriage return and line feed (CRLF) characters to be injected into HTTP/2 header fields. When requests are downgraded from HTTP/2 to HTTP/1.1, the library fails to enforce proper header validation, which may lead to incorrect parsing of request boundaries by downstream components.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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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.