Tailscale says it's patching 11 unpatched flaws found in its SSH server and control server

Tailscale says it is working to patch almost a dozen vulnerabilities in its mesh VPN software and the self-hosted headscale control server, after researchers published details of flaws that had no fixes at the time of disclosure.

Cyberdione Labs founder Erica Windisch said the 11 issues, collectively named Tailworm, were found during an audit and verified by reproduction in a lab on unmodified released software: tailscale v1.104.2 and headscale v0.29.5. The researchers said they released details publicly because they believe rapid awareness will speed up remediation, and that the flaws were discovered "with low effort."

The most critical finding sits in Tailscale's embedded SSH server, which runs as root. According to the write-up, Unix-socket forwarding performs path checks and file operations as root, and races plus a missing privilege drop could let an ordinary session replace, dial or delete privileged resources. The researchers say that requires one approved device and one SSH policy rule, and could lead to root execution on target servers, capture of enrollment keys and arbitrary root-file deletion.

Other findings described in the report cover experimental app connectors that don't validate the true destination against network ACLs, unauthenticated resource exhaustion against headscale, unbounded reads from a hostile DERP relay, and a gap in tailscale serve TCP forwarding to a unix socket.

Tailscale confirmed the reports are "serious" and said exploitation depends on granted permissions, configuration and other conditions. It said it was still verifying the full scope and which configurations are affected, and aimed to ship a fix by the end of Tuesday, October 27.

The company's Mike Shaver said Tailscale is not recommending that everyone disable Tailscale SSH. Its suggested mitigations: review and tighten SSH access policies so only users and devices that need access can connect, and, if forwarding isn't needed, set TS_SSH_DISABLE_FORWARDING=1 in the tailscaled service environment and restart the service. Tailscale said that setting disables forwarding without turning off Tailscale SSH and mitigates several of the more serious findings.

Defenders running Tailscale or headscale should treat the vendor's guidance as the current baseline, check whether SSH forwarding is actually needed, and apply the patched client release when it lands. Self-hosted headscale operators should note that the reported control-server issue needs no account, only internet reachability.