Description: An issue in the Tailscale coordination server allowed individuals creating a new Tailscale account with a gmail.com email address to join the same tailnet, rather than individual tailnets.
There was a flaw in Tailscale’s logic for migrating accounts between identity providers, and a new gmail.com shared tailnet was accidentally created. Once created, any user who tried to create a new Tailscale account with a gmail.com email address joined the shared gmail.com tailnet.
Who is affected?
A total of 44 users with 59 devices who created accounts for their gmail.com email addresses on 2022-05-11 between 10:56 and 13:12 PT were affected. We have notified affected users.
What is the impact?
Six connections between devices belonging to different users were made, but no traffic of concern flowed between them. Four connections were pings, and two connections were UDP traffic on port 27036, likely automated broadcasting by a gaming platform to discover peers to play with. There is no evidence of malicious traffic.
Impacted users could see some metadata about other users and devices from their devices’ clients, including users’ names, devices’ host names, and devices’ Tailscale IP addresses. This information was viewed by at least one user, who reported it to us.
One user, the tailnet Admin, was able to see all users and devices added to the shared gmail.com tailnet. This includes users’ email addresses, names, and when they were last connected; and devices’ host names, their OS and version, when the devices were last connected, and their public IP addresses. This information was viewed by the user, who reported it to us.
What do I need to do?
No action is required. Tailscale has deployed a fix to the coordination server as of 2022-05-11 13:12 PT.
New users registering for a Tailscale account with a gmail.com email address will create a single-user tailnet as normal.
We would like to thank David Swafford and George Constantinides for reporting the issue.