### 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: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### 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!
### 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: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### 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!
Update github.com/coder/coder/v2 to 2.34.2; github.com/coder/coder/v2 to 2.33.8; github.com/coder/coder/v2 to 2.32.7; github.com/coder/coder/v2 to 2.29.17 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanCoder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator affects github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go). Severity is high. ### 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: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### 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!
AI coding agents often install or upgrade packages automatically in go. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/coder/coder/v2go | >=2.34.0,<2.34.2 | 2.34.2 |
| github.com/coder/coder/v2go | >=2.33.0,<2.33.8 | 2.33.8 |
| github.com/coder/coder/v2go | >=2.30.0,<2.32.7 | 2.32.7 |
| github.com/coder/coder/v2go | <2.29.17 | 2.29.17 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate github.com/coder/coder/v2 to 2.34.2; github.com/coder/coder/v2 to 2.33.8; github.com/coder/coder/v2 to 2.32.7; github.com/coder/coder/v2 to 2.29.17 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanCoder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator affects github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go). Severity is high. ### 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: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### 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!
AI coding agents often install or upgrade packages automatically in go. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/coder/coder/v2go | >=2.34.0,<2.34.2 | 2.34.2 |
| github.com/coder/coder/v2go | >=2.33.0,<2.33.8 | 2.33.8 |
| github.com/coder/coder/v2go | >=2.30.0,<2.32.7 | 2.32.7 |
| github.com/coder/coder/v2go | <2.29.17 | 2.29.17 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard