GHSA-5x3r-wrvg-rp6q Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced

• Maven io.netty:netty-codec-http2: >= 4.2.0.Final, < 4.2.15.Final → fixed in 4.2.15.Final • Maven io.netty:netty-codec-http2: < 4.1.135.Final → fixed in 4.1.135.Final

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