GHSA-5x3r-wrvg-rp6q

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GHSA-5x3r-wrvg-rp6q

Summary: Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced

Details: ### Impact 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. ### Resources https://www.rfc-editor.org/rfc/rfc7540.html#section-6.5.2

References: https://github.com/netty/netty/security/advisories/GHSA-5x3r-wrvg-rp6q, https://nvd.nist.gov/vuln/detail/CVE-2026-47244, https://github.com/netty/netty, https://github.com/netty/netty/releases/tag/netty-4.1.135.Final, https://github.com/netty/netty/releases/tag/netty-4.2.15.Final