TS-2026-016
Vulnerability from tailscale - Published: Mon, 26 Oct 2026 00:00:00 GMT
Description: tailscale serve Unix backends could reach privileged sockets, including the tailscaled local API socket.
What happened?
Tailscale Serve can proxy incoming connections to local backends, including Unix domain sockets, making them accessible over your tailnet. Two weaknesses existed in how tailscale serve handled Unix backend targets. First, TCP forwards to Unix sockets lacked a guard and dialed the target as root. This allowed raw bytes to be passed directly into the local API socket using the daemon's own user permissions. Second, the symlink guard for HTTP proxies only ran during configuration reload rather than per dial. A user could replace a benign backend path with a symlink after configuration to defeat this guard.
Tailscale now restricts TCP forwards to the tailscaled socket and revalidates backend targets during each dial.
This vulnerability is fixed in Tailscale version 1.104.4 or newer.
What was the impact?
The first issue allowed full node takeover by providing remote access to the local API. The second issue allowed root-context dials of arbitrary root-only Unix sockets.
Who was affected?
This affects nodes where a local operator has the ability to write serve configurations or where local users have write access to configured backend paths.
What do I need to do?
If you use Tailscale Serve with Unix socket backends, upgrade to Tailscale version 1.104.4 or newer.
Show details on source website{
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Sightings
| Author | Source | Type | Date | Other |
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Nomenclature
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- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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Vulnerability timeline
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Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
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