CVE-2026-59899: netty

Vulnerability summary

CVE-2026-59899 is a high (CVSS 7.5) vulnerability in netty. EPSS estimates a 0.61% chance of exploitation in the next 30 days, higher than 48.1% of scored vulnerabilities.

Timeline

1. 29-07-2026
   PublishedVulnerability first disclosed.
2. 30-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-770Allocation of Resources Without Limits or ThrottlingThe product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.