What happened
When sshd is built without PAM (musl libc), it hashes the supplied password with crypt() and compares to the stored field; for accounts whose password field is '*' (key-only / no password), the long-password (256-1024 char) case is misread and allows authentication. Exploitation began within ~9 hours of disclosure; added to CISA KEV on 2026-11-09 (due 2026-11-12).
Why it matters
A one-shot, unauthenticated authentication bypass on the Alpine/musl images many teams use to run model-serving, ML tooling and AI container workloads gives an attacker an interactive shell on the host running AI infrastructure, and the same compressed time-to-exploit window the prompt flags for AI-driven weaponization. KEV operational signal mandates immediate patching.
Attack vector
A remote unauthenticated attacker who can reach the SSH port sends a 256–1024 character password to an account whose /etc/shadow password field is '*' (an account with no password set), which sshd without PAM misinterprets and accepts — authentication bypass in one connection with no retries
Affected systems
OpenSSH before 10.6p2 on Linux built with musl libc without PAM (Alpine Linux); Alpine openssh-server packages on branches 3.16–3.24 and edge (fixed: 3.21.10, 3.22.8, 3.23.8, 3.24.4, edge 10.6_p2-r0)
Mitigation
Update openssh to the fixed version per branch and restart sshd (upgrading the package does not restart it); or set PasswordAuthentication no; or use openssh-server-pam with UsePAM yes; review sshd logs for 'Accepted password' on passwordless accounts, and treat exposed hosts as compromised if a login cannot be ruled out (https://alpinelinux.org/posts/2026-11-05-openssh-password-authentication-bypass/)