CVE-2026-75596

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, the default io.netty.handler.ssl.SniHandler constructors use the pre-handshake ClientHello aggregation path in handler/src/main/java/io/netty/handler/ssl/SslClientHelloHandler.java at io.netty.handler.ssl.SslClientHelloHandler#decode, where handshakeBuffer.clear() and writeBytes() recopy all previously received body bytes for every additional TLS record. An unauthenticated remote peer can advertise a large ClientHello and deliver its body in thousands of tiny records, causing quadratic CPU work on the event loop before the TLS handshake completes and degrading TLS handling for other clients. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

CVSS

No CVSS.

References

Link	Resource
https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7
https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961
https://github.com/netty/netty/pull/17213
https://github.com/netty/netty/pull/17217
https://github.com/netty/netty/releases/tag/netty-4.1.137.Final
https://github.com/netty/netty/releases/tag/netty-4.2.17.Final
https://github.com/netty/netty/security/advisories/GHSA-fccg-mwvh-qqg4

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-19 21:17

Updated : 2026-09-09 21:19

NVD link : CVE-2026-75596

Mitre link : CVE-2026-75596

CVE.ORG link : CVE-2026-75596

JSON object : View

Products Affected

No product.

CWE

CWE-407

Inefficient Algorithmic Complexity

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