*sshole, or when are we finally going to get rid of C? · sunshowers

A critical authentication bypass in musl libc’s `crypt` function has exposed Alpine Linux systems—including the official Alpine AWS image—to unauthenticated remote root shells. The flaw arises because musl returns the sentinel string `"*"` for overlong passwords, a value that Unix has long used to denote locked accounts; when sshd hashes login attempts for locked accounts to avoid timing leaks, the two conventions collide and any password is accepted. The bug is not a memory-safety issue but an in-band signaling failure that the C type system cannot prevent, since callers are not forced to check for a null return as POSIX specifies. It matters because Alpine’s minimal, PAM-free images are widely used in containers and cloud workloads, so a single misread sentinel can silently grant root access. Watch for patched musl releases and Alpine image rebuilds, and for renewed debate over Rust-style result types and distro maintainers’ resistance to Rust dependencies.