Описание
Coder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator
Summary
The tailnet coordinator validates that an agent's Addresses derive from its authenticated UUID but applies no equivalent check to AllowedIPs. The coordinator forwards agent-supplied AllowedIPs verbatim to tunnel peers which install them into the WireGuard peer configuration.
Impact
A malicious workspace agent can advertise arbitrary AllowedIPs prefixes including another agent's tailnet address. Coder's ServerTailnet routes to agents by tailnet IP so an agent that claims a victim's prefix can intercept web terminal and workspace app traffic and serve spoofed content. Exploitation requires an authenticated user with a running workspace and a modified agent binary.
Patches
The fix validates each AllowedIPs prefix against the authenticating agent's UUID just like Addresses.
The fix was backported to all supported release lines:
Workarounds
Operators who cannot upgrade immediately should monitor coordinator logs for agents advertising unexpected AllowedIPs prefixes.
Resources
- Fix: #26144
Credits
Coder would like to thank Anthropic's Security Team (ANT-2026-22451) for independently disclosing this issue!
Пакеты
github.com/coder/coder/v2
>= 2.34.0, < 2.34.2
2.34.2
github.com/coder/coder/v2
>= 2.33.0, < 2.33.8
2.33.8
github.com/coder/coder/v2
>= 2.30.0, < 2.32.7
2.32.7
github.com/coder/coder/v2
< 2.29.17
2.29.17
Связанные уязвимости
Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the tailnet coordinator validates that an agent's `Addresses` derive from its authenticated UUID but applies no equivalent check to `AllowedIPs`. The coordinator forwards agent-supplied `AllowedIPs` verbatim to tunnel peers which install them into the WireGuard peer configuration. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 validates each `AllowedIPs` prefix against the authenticating agent's UUID just like `Addresses`. As a workaround, monitor coordinator logs for agents advertising unexpected `AllowedIPs` prefixes.