Bug 2541820 (CVE-2026-100665)

Summary: CVE-2026-100665 io.netty/netty-codec-classes-quic: io.netty/netty-codec-quic: netty: Hostname verification bypass via incomplete QUIC certificate validation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: sdawley
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Netty. During certificate validation for Quick UDP Internet Connections (QUIC), standard trust managers fail to perform endpoint identification to confirm the server's identity. A remote attacker positioned on the network path can exploit this flaw by presenting a valid certificate for an unrelated domain during connection establishment. This allows the attacker to bypass hostname verification, impersonate trusted servers, and intercept sensitive communications.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-09-26 13:32:45 UTC
Netty versions from 4.2.11.Final before 4.2.18.Final contain an incomplete hostname verification fix in the QUIC certificate verification path when using a plain X509TrustManager. The BoringSSLCertificateVerifyCallback discards the SSLEngine for plain trust managers, preventing endpoint identification from running even when HTTPS verification is configured. Attackers on the network path can present a certificate chain for the wrong hostname that the plain trust manager accepts, bypassing hostname authentication for QUIC clients.