Netty HttpContentCompressor Resource Exhaustion via Unbounded acceptEncodingQueue < 4.1.136
CVE-2026-59899 Published on July 29, 2026
Netty HttpContentEncoder: Unbounded Per-Connection Queue Growth via HTTP/1.1 Pipelining Leads to Denial of Service
Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, `HttpContentEncoder` (the superclass of the production handler `HttpContentCompressor`) maintains a per-channel `ArrayDeque<CharSequence>` named `acceptEncodingQueue` that accumulates attacker-controlled data without any size limit. The queue is filled on the I/O thread for every inbound HTTP request and drained only when the application later writes a non-1xx response. This creates a resource exhaustion vulnerability when an attacker exploits HTTP/1.1 pipelining to flood the connection with requests faster than the application produces responses. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.
Weakness Type
Allocation of Resources Without Limits or Throttling
The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.
Products Associated with CVE-2026-59899
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Affected Versions
netty:- Version >= 4.2.0.Final, < 4.2.16.Final is affected.
- Version < 4.1.136.Final is affected.