Tailscale says most of its SSH bugs are privilege escalations, and a patch was due October 27 (tailscale.com)
The vulnerabilities let a user already authorized over Tailscale SSH act beyond their configured local user. Fixes are built and in testing, and in the meantime Tailscale suggests setting TS_SSH_DISABLE_FORWARDING=1 in the tailscaled environment, which it says mitigates several serious findings.
A former Tailscale employee in the thread narrowed who is exposed.