Coder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator

Summary

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.

Timeline

1. Jul 7, 2026, 11:57 PM UTCCVE published
2. Jul 8, 2026, 1:10 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Jul 8, 2026, 1:11 PM UTCRecord last updated

Affected versions

• coder coder

  From 2.34.0 · fixed in 2.34.2; From 2.33.0 · fixed in 2.33.8; From 2.30.0 · fixed in 2.32.7; fixed in 2.29.17

• github.com/coder/coderGo

  All versions

• github.com/coder/coder/v2Go

  fixed in 2.29.17; From 2.30.0 · fixed in 2.32.7; From 2.33.0 · fixed in 2.33.8; From 2.34.0 · fixed in 2.34.2

• github.com/coder/coder/v2Go

  From 2.34.0 · fixed in 2.34.2

• github.com/coder/coder/v2Go

  From 2.33.0 · fixed in 2.33.8

• github.com/coder/coder/v2Go

  From 2.30.0 · fixed in 2.32.7

• github.com/coder/coder/v2Go

  fixed in 2.29.17

References 6