CVE-2025-58369 – fs2: Half-shutdown of socket during TLS handshake may result in spin loop on opposite side

fs2 is a compositional, streaming I/O library for Scala. Versions 3.12.2 and lower and 3.13.0-M1 through 3.13.0-M6 is vulnerable to denial of service attacks though TLS sessions using fs2-io on the JVM using the fs2.io.net.tls package. When establishing a TLS session, if one side of the connection shuts down `write` while the peer side is awaiting more data to progress the TLS handshake, the peer side will spin loop on the socket read, fully utilizing a CPU. The CPU is consumed until the overall connection is closed, potentially shutting down a fs2-io powered server. This issue is fixed in versions 3.12.1 and 3.13.0-M7.