Description
Netty is an asynchronous, event-driven network application framework. Prior to 4.1.136.Final and 4.2.16.Final, io.netty.handler.codec.xml.XmlFrameDecoder.decode() failed to preserve closing-tag parser state across invocations, so an unauthenticated remote attacker could trickle-feed repeated </ sequences that repeatedly rescanned the accumulated buffer and exhausted an EventLoop thread's CPU, causing denial of service with a maxFrameLength of 1 MB. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
Affected products
netty: netty
References5
- github.com/netty/netty/security/advisories/GHSA-v74w-7mr3-4qg3 Vendor Advisory
- github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea23965… Patch
- github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52a… Patch
- github.com/netty/netty/releases/tag/netty-4.1.136.Final Release Notes
- github.com/netty/netty/releases/tag/netty-4.2.16.Final Release Notes
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 57 · as of 12 November 2026
- CWE
- CWE-400
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.