CVE-2026-55831 [HIGH] – Netty is a network application framework for development of protocol servers and clients.

Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty’s SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in `DefaultSpdySettingsFrame`, allowing a remote SPDY/3.1 peer to send a syntactically valid roughly 2 MiB SETTINGS frame that creates 262144 map entries and amplifies network input into heap growth and ordered-map insertion work. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.