Critical Linux Kernel Flaw ‘ssh-keysign-pwn’ Exposes SSH Keys and Shadow Passwords

A logic flaw in the Linux kernel ptrace access control (CVE-2026-46333, "ssh-keysign-pwn") creates a race window where an unprivileged local attacker can use pidfd_getfd to steal file descriptors from privileged helpers (e.g., ssh-keysign, chage), enabling theft of SSH host keys and /etc/shadow password hashes; a public GitHub PoC exists, many distributions are affected, and immediate patching, key rotation, and access restrictions are recommended.