Bug 2488380 (CVE-2026-44894)

Summary: CVE-2026-44894 netty-codec-classes-quic: Netty: Denial of Service amplification via improper QUIC token validation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abrianik, ggrzybek, jraez, parichar, tasato
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Netty, specifically within the netty-codec-classes-quic component's NoQuicTokenHandler. A remote attacker can exploit this vulnerability by sending an Initial packet with any non-empty token bytes and a spoofed victim's IP address. This improper token validation causes the Netty server to bypass the 3x anti-amplification send limit, treating the victim as validated. As a result, the server reflects full-size handshake flights towards the spoofed victim, leading to an amplification attack.
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Description OSIDB Bzimport 2026-06-12 15:01:31 UTC 
Netty is a network application framework for development of protocol servers and clients. NoQuicTokenHandler is the tokenHandler used when the application does not set one. Prior to version 4.2.15.Final, its writeToken() returns false (server will not send Retry — acceptable), but validateToken() unconditionally `return 0`. In QuicheQuicServerCodec.handlePacket(), a non-negative return from validateToken() is interpreted as 'token is valid, ODCID starts at offset 0', causing the server to call quiche_accept as if the client's address had been validated by a Retry round-trip. Per RFC 9000 §8.1, a validated address lifts the 3× anti-amplification send limit. Thus any attacker who includes ANY non-empty token bytes in an Initial packet — with a spoofed victim source IP — causes the Netty server to treat the victim as validated and reflect full-size handshake flights (certificates, etc.) toward it without the 3× cap. The correct 'no token handler' semantics would be to return -1 (invalid) so the normal un-validated path and amplification limit apply. Version 4.2.15.Final patches the issue.