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CVE-2026-50009 netty CVE debrief

CVE-2026-50009 is a vulnerability in Netty, a network application framework. Prior to version 4.2.15.Final, Netty QUIC exposes the stateless reset token on the network path when using the default HMAC-based connection-ID and stateless-reset-token generators. This allows an on-path attacker to derive the reset token for the server's current source connection ID from bytes that appear as the connection ID in QUIC headers after a source-CID rotation. The attacker can then use the token to perform a Denial of Service by sending a spoofed Stateless Reset packet. The CVSS score for this vulnerability is 4.8, indicating a medium severity.

Vendor
netty
Product
Unknown
CVSS
MEDIUM 4.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-12
Original CVE updated
2026-06-15
Advisory published
2026-06-12
Advisory updated
2026-06-15

Who should care

Users of Netty QUIC prior to version 4.2.15.Final should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by the exposure of the stateless reset token on the network path. This allows an attacker to derive the token and send a spoofed Stateless Reset packet, resulting in a Denial of Service.

Defensive priority

Medium

Recommended defensive actions

  • Upgrade to Netty version 4.2.15.Final or later.
  • Use a different connection-ID and stateless-reset-token generator.

Evidence notes

The CVE record [cve-org] and NVD detail [nvd] provide information on this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-50009 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-50009

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-50009 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-50009

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.