Netty: QUIC stateless reset token material exposed through header-visible connection IDs

Exploitation

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

CVSS

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

EPSS

• CVE-2026-50009: 0.20% estimated exploitation activity in the next 30 days; percentile 10.38 (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.

Summary Netty QUIC exposes the stateless reset token on the network path when using the default HMAC-based connection-ID and stateless-reset-token generators. The reset token for the server's current source connection ID can be derived from bytes that appear as the connection ID in QUIC headers after a source-CID rotation. An on-path attacker observing the headers can use the token to perform a Denial of Service by sending a spoofed Stateless Reset packet. Details The sign-based connection ID generator (HmacSignQuicConnectionIdGenerator) and reset token generator (HmacSignQuicResetTokenGenerator) both evaluate HMAC-SHA256 with the same JVM-wide static key (io.netty.handler.codec.quic.Hmac). During source CID rotation (QuicheQuicChannel.newSourceConnectionIds), the current server source CID C is used as input to produce the next CID N. The stateless reset token for C is defined over HMAC(K, C), specifically the first 16 bytes. The next CID N is the first L bytes of the same digest,…

Published by the source

15 Jun 2026, 20:44 UTC

Last modified by the source

15 Jun 2026, 20:44 UTC

Source last checked

26 Oct 2026, 16:53 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cq4q-cv5g-r8q5

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# Patch Next advisory brief: CVE-2026-50009

Advisory: Netty: QUIC stateless reset token material exposed through header-visible connection IDs
IDs: CVE-2026-50009, GHSA-cq4q-cv5g-r8q5
Record: https://patchnext.com/advisories/cve-2026-50009 (revision 1, source checked 26 Oct 2026, 16:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.8)
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-cq4q-cv5g-r8q5 (GitHub-reviewed advisory GHSA-cq4q-cv5g-r8q5 lists affected ranges: Maven io.netty:netty-codec-classes-quic >=4.2.0.Final <=4.2.14.Final)

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