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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-44894: 0.14% estimated exploitation activity in the next 30 days; percentile 3.62 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 quicheaccept 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.

Published by the source

8 Jun 2026, 22:59 UTC

Last modified by the source

12 Jun 2026, 19:29 UTC

Source last checked

26 Oct 2026, 16:46 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cmm3-54f8-px4j

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# Patch Next advisory brief: CVE-2026-44894

Advisory: Netty's Default QUIC token handler accepts any client-supplied token
IDs: CVE-2026-44894, GHSA-cmm3-54f8-px4j
Record: https://patchnext.com/advisories/cve-2026-44894 (revision 1, source checked 26 Oct 2026, 16:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: io.netty:netty-codec-classes-quic 4.2.15.Final. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven io.netty:netty-codec-classes-quic: affected >= 4.2.0.Final, <= 4.2.14.Final; fixed in 4.2.15.Final

## Suggested inspection (read-only)
- Maven io.netty:netty-codec-classes-quic: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on io.netty:netty-codec-classes-quic.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cmm3-54f8-px4j (GitHub-reviewed advisory GHSA-cmm3-54f8-px4j lists affected ranges: Maven io.netty:netty-codec-classes-quic >=4.2.0.Final <=4.2.14.Final)

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