ALERT · Patch available. Last updated 28 October 2026. See the Alert Tracker
If you run Tailscale SSH or Serve, upgrade to 1.104.4 or newer. Tailscale published four bulletins on 26 October covering socket forwarding, SSH DoS, Serve Unix backends, and HTTP/2 capability bleed.
What it is
TS-2026-014 (opens in a new tab) to 017 (opens in a new tab): SSH Unix forwarding that could reach root-only sockets; SSH session memory exhaustion (DoS); tailscale serve Unix backends that could reach privileged sockets including the local API; and HTTP/2 Serve context sending the wrong Tailscale-App-Capabilities across mounts. All fixed in 1.104.4. Independent research (press nickname “Tailworm”) described a broader finding set; Tailscale has not assigned CVEs for these four, and we have not verified any “eleven flaws” count against vendor advisories.
Who is affected
Nodes on versions before 1.104.4 that use Tailscale SSH and/or Serve (especially TLS Serve with multiple capability-scoped mounts, or Unix-socket backends). See each bulletin’s affected section.
Exploitation status
No CVEs in the bulletins, so no KEV row. Tailscale has not reported in-the-wild use of these four. Tracker status is Patch available because all four published bulletins are fixed in 1.104.4; public research claims of further issues remain unverified against vendor advisories.
Fix and mitigation
Upgrade clients and tailscaled to 1.104.4+. Until then, tighten SSH/Serve ACLs, avoid privileged Unix sockets via Serve, and limit concurrent capability-scoped mounts on one node.
How to hunt
Inventory versions (tailscale version / MDM). Review Serve configs for Unix backends on privileged sockets and multi-mount capability setups. No Hunt Lab rule in this pack.
Sources
- TS-2026-014 (opens in a new tab)–017 (opens in a new tab) (26 October 2026)
- Tailscale blog — findings and fixes (opens in a new tab)
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