Tailscale says version 1.104.4 fixes the privilege flaws in Tailscale SSH that a security researcher described in a report called Tailworm.
According to Tailscale’s findings post, written by Mike Shaver, the company received the report on the morning of Saturday, October 24, and the researcher published it two hours later. Tailscale says the SSH flaws concerned how permissions were enforced after a connection had already been authorized. Under certain conditions, an authenticated SSH session could do things beyond the privileges of its configured local user, including through SSH forwarding.
Tailscale states that exploitation requires an attacker to already hold an authorized device in the tailnet, with SSH access explicitly permitted in the tailnet policy file. It says the flaws do not let an unauthenticated attacker connect to arbitrary Tailscale SSH servers. The company also rejects the worm label in the report’s name, writing that the activity “would be better described as lateral movement limited to connections allowed by a tailnet policy file.”
Tailscale published four security bulletins, TS-2026-014 through TS-2026-017. The report also listed five findings in Tailscale Serve and Funnel. Tailscale says three were bugs fixed in the same release and two describe behavior that works as designed. A further issue sits in Conn25, an app connector feature that Tailscale says is still in pre-production and unreleased; it says the stable app connectors are not affected.
Tailscale recommends updating to v1.104.4 or later, reviewing Tailscale SSH policies so access is limited to the users and devices that need it, and considering SSH check mode for sensitive systems, which adds an authentication check before access is granted.
In our reading, the patch repairs the privilege boundary and the policy file decides how far one compromised device can travel. That matters because a single foothold is how recent incidents began, such as the token replay that reached 79 Microsoft 365 organizations and the Microsoft Authenticator token flaw on Android. A tailnet policy that lists every device as a source for every server gives a stolen laptop the same reach as an administrator’s.
Source: Tailscale
