Netty HTTP/2 Max Header Size Bug before 4.1.135/4.2.15 (CVE-2026-50560)
CVE-2026-50560 Published on June 12, 2026
Netty susceptible to HTTP/2 Reset Attack with different on-the-wire signature
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, Netty HTTP/2 max header size handling produces an attack similar to HTTP/2 Rapid Reset. There is a setting in the http2 specification called `SETTINGS_MAX_HEADER_LIST_SIZE`. When a client sends that setting to Netty, it appears that Netty will behave as follows: read the request; proxy the request to the origin; attempt to produce a response; and create an exception while writing the headers for the response. Functionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature. Versions 4.1.135.Final and 4.2.15.Final patch the issue.
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-2026-50560
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Affected Versions
netty:- Version >= 4.2.0.Final, < 4.2.15.Final is affected.
- Version < 4.1.135.Final is affected.