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TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

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Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#61
post #24

I'll stick to my 100% self-hosted Wireguard setup, thank you very much.

Why not tailscale plus head scale for self hosting?

I also tested tailscale, headscale and netbird and found all these drain your battery on mobile.

Others report no issues but I had massive drain on iOS even with only 4 connections open.

Native wireguard is unnoticeable.

Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#62
I don't see the point of publishing a security bulletin if you are not going to timely push the fix to artifacts on all affected platforms. Tailscale needs to do better on their release process, docker hub shows last update was 8 days ago.

Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#63
post #53

I’m a heavy Tailscale user, so I do trust them quite a bit, but I never used the Tailscale SSH feature. I feel like OpenSSH’s security record is pretty unbeatable, not sure why I’d swap over for such a security-sensitive tool.

The SSH vulnerability here only applies if the attacker is already on the network. It violates your Tailscale ACLs, but it's not arbitrary external root ssh access. Arguably that's a more secure starting point than vanilla ssh to publicly accessible machine.

OTOH, if you run vanilla ssh on a publicly accessible machine where only port 22 is open, sshd only allows publickey-based authentication and the only accepted key types are FIDO2/U2F hardware-backed keys, it's probably more secure again (less attack surface).

Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#64
post #53

I’m a heavy Tailscale user, so I do trust them quite a bit, but I never used the Tailscale SSH feature. I feel like OpenSSH’s security record is pretty unbeatable, not sure why I’d swap over for such a security-sensitive tool.

The SSH vulnerability here only applies if the attacker is already on the network. It violates your Tailscale ACLs, but it's not arbitrary external root ssh access. Arguably that's a more secure starting point than vanilla ssh to publicly accessible machine.

With a plain VPN like WireGuard when they get access to your network, they don't have plain ssh, not to mention root ssh access to hosts. This is a serious issue.

Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#65

Earlier quoted context omitted.

Why not tailscale plus head scale for self hosting?

I do not understand this rebuttal. I also run self-hosted Wireguard. Initially on a Debian box, nowadays it is integrated into my router (admittedly, this is closed source). For around 6 years at this point. The whole thing could not be easier and simpler. It has never randomly broken on me. It is fast. It is free. There is no middle man, no vendor. I never understood the popularity of Tailscale, though that is on me…

it wasn't meant as a rebuttal, I'm genuinely asking. tailscale + headscale was just recommended to me, hence that's what I'm using for self hosting. is wireguard's client roughly equivalent to tailscale's? especially tailscale's always-on nature is very appealing.

Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#66

Earlier quoted context omitted.

I'm somewhat alarmed that the context that this bug was running in was capable of root login. Is there a reason that an SSH login process would, by default, have enough capabilities to facilitate direct root login?

We did Tailscale-like SSH reverse tunnels at scale first in 2013 and the main issue has always been that there are no good libraries. Bash scripting around the OpenSSH binaries is pretty much the only way to go. There's Paramiko, but Python is still a huge liability in memory-constrained systems.

libssh, libssh2. These are totally independent and unrelated code bases, libssh is maintained by Red Hat mainly for ansible and some other tools, libssh2 was created for curl. libssh2 is client-only, libssh can also be used to implement servers.

Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#67

I don't see the point of publishing a security bulletin if you are not going to timely push the fix to artifacts on all affected platforms. Tailscale needs to do better on their release process, docker hub shows last update was 8 days ago.

so you can disable or mitigate it…

Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#69

Earlier quoted context omitted.

Why not tailscale plus head scale for self hosting?

I do not understand this rebuttal. I also run self-hosted Wireguard. Initially on a Debian box, nowadays it is integrated into my router (admittedly, this is closed source). For around 6 years at this point. The whole thing could not be easier and simpler. It has never randomly broken on me. It is fast. It is free. There is no middle man, no vendor. I never understood the popularity of Tailscale, though that is on me…

My WireGuard uses (either at home or at work) are very much mobile client to single network

Where Tailscale comes into its own is automatic managing of mesh networking (like an “sdwan” solution). The other thing it excels at is firewall busting - if you have a firewall (with or without address translation) which only allows outgoing traffic to be established (with UDP timeouts for session) then Tailscale also works in a similar way to turn/stun.

If I needed that capability then I’d be looking at Headscale. I don’t need it though.

Remember that this is hackernews, not slashdot. Where the community used to be far smaller and the technology far smaller it was quite normal for everyone to understand basic building blocks of ip addresses, use open source software, wear t-shirts threatening to replace people with a small shell script etc.

It’s not the same community, many people here have no real understanding of computer fundamentals, but instead have expertise in specific narrow areas. They also have little interest in things like free software, but do have an interest in building a new billion dollar company to sell to a behemoth.

Re: TS-2026-009: Insecure argument handling in Tailscale SSH permitted root access

#70
post #24

I'll stick to my 100% self-hosted Wireguard setup, thank you very much.

haha self hosted wireguard, an opportunity to find out AllowedIPs: 0.0.0.0/0 does the opposite of what you think it will do

Allow any (ip4) traffic to enter the tunnel, install a route in the default routing table to make that happen (well the second depends on the client)

Does it do the opposite of that?

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