CVE-2026-47244
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk39th percentile — higher than 39% of all known CVEs
Summary
Netty, a network application framework, prior to versions 4.1.135.Final and 4.2.15.Final, does not limit the number of active streams in HTTP/2, potentially leading to excessive resource consumption. The lack of a default limit on the maximum number of streams can result in the creation of hundreds of thousands of stream objects in a single TCP connection.
Risk Assessment
Organizations may experience significant performance and stability issues with their servers, potentially leading to service outages. Increased backend load due to the absence of a stream limit may also raise operational costs.
Recommendation
It is recommended to upgrade to versions 4.1.135.Final or 4.2.15.Final to patch this vulnerability. Additionally, configuring a maximum number of concurrent streams in the application is advisable to prevent excessive resource consumption.
Original NVD description (English source)
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.