This is not rare. Every TCP connection in Go by default enables MPTCP [1]. Simply running a Go program that uses TCP without explicitly disabling this behavior will cause the running kernel to be vulnerable.
reply1: https://groups.google.com/g/golang-announce/c/PCoQcdxoScw
But any sane configuration would have the MPTCP port blocked behind a firewall (unless you were intentionally using MPTCP).
reply> MPTCP port blocked
replyMPTCP doesn’t use any specific ports. It’s an OSI layer higher than that. It’s part of the TCP protocol itself. So if your firewall routes TCP traffic of a specific port (eg HTTP) already then it’ll route MPTCP along with it too.
MPTCP is a protocol extension that requires cooperation by both peers and all middleboxes. So, if there is a Layer 7 firewall, or DPI/SPI, or TLS termination on the path, and it's not inclined to preserve the MPTCP options, then MPTCP will be disabled.
replyTry:
reply sudo ss -lnp -A mptcp
It seems like the anthropic PoC involves MPTCP, but the bug itself is not in the MPTCP code, it's in a generic TCP codepath relating to options, MPTCP was probably just a convenient codepath for memory manipulation.
replycontainerd (docker) uses it
reply