Bitcoin Core and Lightning developer Matt Corallo has disclosed a critical vulnerability (CVE-2026-98432, CVSS score 9.8) in the Linux kernel's IPv4 TCP handshake code, which the Anthropic team demonstrated can be exploited for remote root attacks. Lightning Labs subsequently released emergency versions `lnd v0.21.6-beta` and `v0.20.7-beta`, disabling the MPTCP listener by default to provide mitigation.