CVE-2026-55428

HIGH

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

Title source: cna
STIX 2.1

Description

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.

References (6)

Core 6
Core References
X_Refsource_Misc x_refsource_misc
https://github.com/coder/coder/pull/26144
X_Refsource_Misc x_refsource_misc
https://github.com/coder/coder/releases/tag/v2.29.17
X_Refsource_Misc x_refsource_misc
https://github.com/coder/coder/releases/tag/v2.32.7
X_Refsource_Misc x_refsource_misc
https://github.com/coder/coder/releases/tag/v2.33.8
X_Refsource_Misc x_refsource_misc
https://github.com/coder/coder/releases/tag/v2.34.2

Scores

CVSS v3 8.2
EPSS 0.0025
EPSS Percentile 16.0%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-285 CWE-863
Status published
Products (4)
coder/coder < 2.29.17 (2 CPE variants)
coder/coder >= 2.30.0, < 2.32.7
coder/coder >= 2.33.0, < 2.33.8
coder/coder >= 2.34.0, < 2.34.2
Published Jul 08, 2026
Tracked Since Jul 08, 2026