Netty prior 4.1.135.Final/4.2.15.Final Http2Settings.java initialSettings resource consumption

Summaryinfo

A vulnerability classified as problematic was found in Netty. The impacted element is the function initialSettings of the file Http2Settings.java. The manipulation results in resource consumption. This vulnerability was named CVE-2026-47244. The attack needs to be approached locally. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Netty. It has been classified as problematic. Affected is the function initialSettings of the file Http2Settings.java. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. CVE summarizes:

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, DefaultHttp2Connection.DefaultEndpoint initialises maxActiveStreams/maxStreams to Integer.MAX_VALUE, and Http2Settings never inserts SETTINGS_MAX_CONCURRENT_STREAMS by default (Http2Settings.java:305-307 only clamps a user-supplied value). Unless the application explicitly calls initialSettings().maxConcurrentStreams(n), a Netty HTTP/2 server advertises no limit and enforces none locally. Each open stream allocates a DefaultStream object, PropertyMap slots, flow-controller state and IntObjectHashMap entry; with ~2^30 permissible odd stream IDs a single TCP connection can create hundreds of thousands of long-lived stream objects. This is also the precondition for CVE-2023-44487-style Rapid-Reset amplification, where the absence of a low concurrent cap multiplies backend work. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-47244 since 05/19/2026. The exploitability is told to be easy. The attack needs to be approached locally. There are known technical details, but no exploit is available.

Upgrading to version 4.1.135.Final or 4.2.15.Final eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1814). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Open Source Netty

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• Netty

Website

• Product: https://github.com/netty/netty/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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