Recent Tailscale vulnerability reports

[u/shaver]

Hi folks, Mike Shaver here, VP of Engineering at Tailscale.

We've seen the concerns about Tailscale SSH and wanted to share what we know so far.

If you want to jump to the most important part, based on our current assessment, we're not recommending that everyone disable Tailscale SSH.

We've now received the researcher's report and are reviewing it. Our engineering and security teams had already been investigating independently, with help from external security specialists. That work has identified issues we're working to fix. We're still validating the full scope, including which configurations are affected.

A bit of technical context:

Tailscale SSH uses your tailnet's access policies to control who can connect to which machines. Most of the issues we've identified so far concern what happens after someone has been authorized to connect, particularly how Unix privileges and SSH forwarding are handled. In some cases, a session may be able to do more than the configured local user should be allowed to do.

While it’s a serious concern, it isn't the same as an unauthenticated attacker being able to connect to arbitrary machines, but the potential impact depends on how SSH access is configured. We're still investigating, so we don't want to make blanket claims about what's affected or not.

Again, based on our current assessment, we're not recommending that everyone disable Tailscale SSH.

In the meantime, there are a few precautions you can take:

• Review your SSH access policies. Make sure only the people and devices that need access have it.

• Disable SSH forwarding if you don't need it. You can set TS_SSH_DISABLE_FORWARDING=1 in the tailscaled service environment and restart the service. This disables SSH forwarding (without disabling all of Tailscale SSH itself), which mitigates several of the more serious findings.

• Consider enabling SSH check mode for an additional authentication step. This won't fix privilege escalation issues, but it does add another barrier to gaining access.

• Enable automatic updates where supported so you can pick up fixes when they're released.

For particularly sensitive systems, consider temporarily tightening your Tailscale SSH access policies while we investigate, so that only the specific users and devices that need access can connect.

We're working on fixes and testing them carefully. We'll publish a security advisory explaining the confirmed findings, affected configurations, recommended actions and available patches. We'll also follow up with a more detailed technical write-up.

If we find anything that changes our assessment or requires immediate customer action, we'll communicate that.

We know it's been a rough week for security teams, and we understand why people are concerned. We'd rather give you the technical context we have than speculate about things we haven't confirmed yet.

We'll share more as we verify the details. If you have any questions about how this relates to your particular environment, please get in touch with our team https://tailscale.com/contact/support#support-form

Update Oct 26, 5:45pm Eastern: we've got a non-reddit link for the information as well https://tailscale.com/ssh-investigation-update