High

Netty's Default QUIC token handler accepts any client-supplied token

  • Disclosed: 08.06.2026
  • Updated: 11.10.2026 13:20

NoQuicTokenHandler is the tokenHandler used when the application does not set one. 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.

Affected software

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PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) io.netty:netty-codec-classes-quic >= 4.2.0.Final, < 4.2.15.Final 4.2.15.Final

References

CVSS score 7.5/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness (CWE)
CWE-940
Platform
Java / Kotlin (Maven)
Package
io.netty:netty-codec-classes-quic
Disclosed
08.06.2026
Updated
11.10.2026 13:20

Sources and licenses

OSV / GitHub Advisory Database - GHSA-cmm3-54f8-px4j - CC BY 4.0

Vulnerability history: io.netty:netty-codec-classes-quic

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries
2
First → latest
06.2026 06.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 1
  • Medium 1

Disclosures per year

  1. 2026: 2
  1. Medium · 4.8 CVE-2026-50009 >= 4.2.0.Final, < 4.2.15.Final 4.2.15.Final
  2. Netty's Default QUIC token handler accepts any client-supplied token this entry
    High · 7.5 CVE-2026-44894 >= 4.2.0.Final, < 4.2.15.Final 4.2.15.Final

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