CVE-2026-44894: netty — Fix

Description

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.

Is your site exposed to CVE-2026-44894?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0014

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-940 CWE-940

Affected Products

Vendor	Product	Versions
netty	netty	4.2.0 — 4.2.15

References

Advisories & Patches

https://github.com/netty/netty/security/advisories/GHSA-cmm3-54f8-px4j

Other References

https://github.com/netty/netty/releases/tag/netty-4.2.15.Final

Frequently Asked Questions

What is CVE-2026-44894? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-44894? +

CVE-2026-44894 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0014, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-44894? +

CVE-2026-44894 affects products from netty, specifically: netty. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-44894? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-59786

Zabbix Server and Proxy accept the active agent heartbeat message regardless of the configured PSK or certificate authentication. This means …

CVE-2025-9999

Some payload elements of the messages sent between two stations in a networking architecture are not properly checked on the …

CVE-2026-123139

Improper verification of the source of a communication channel vulnerability in Opera Neon on macOS and Windows allows a malicious …

CVE-2026-101897

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. From 1.20.0 until …

CVE-2026-0325

An authorization bypass vulnerability in the GlobalProtect gateway of Palo Alto Networks PAN-OS® software enables an authenticated attacker with valid …

CVE-2026-89409

In Z-Wave SDK 8.1.1 and earlier (for 700/800 series devices) and 6.85.02 and earlier (for 500 series devices), missing checks …