CVE-2026-75596
Description
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
io.netty:netty-handlerMaven | >= 4.2.0.Final, < 4.2.17.Final | 4.2.17.Final |
io.netty:netty-handlerMaven | < 4.1.137.Final | 4.1.137.Final |
Affected products
1Patches
Vulnerability mechanics
References
9- github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7nvdPatchWEB
- github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961nvdPatchWEB
- github.com/netty/netty/pull/17213nvdIssue TrackingPatchWEB
- github.com/netty/netty/pull/17217nvdIssue TrackingPatchWEB
- github.com/advisories/GHSA-fccg-mwvh-qqg4ghsaADVISORY
- github.com/netty/netty/security/advisories/GHSA-fccg-mwvh-qqg4nvdVendor AdvisoryWEB
- nvd.nist.gov/vuln/detail/CVE-2026-75596ghsaADVISORY
- github.com/netty/netty/releases/tag/netty-4.1.137.FinalnvdRelease NotesWEB
- github.com/netty/netty/releases/tag/netty-4.2.17.FinalnvdRelease NotesWEB
News mentions
1- Netty Framework: Nine Vulnerabilities Disclosed, Including DoS and Information ExposureVypr Intelligence · Aug 22, 2026