Coder up to 2.29.16/2.32.6/2.33.7/2.34.1 Tailnet Coordinator AllowedIPs input validation

Summaryinfo

A vulnerability classified as critical was found in Coder up to 2.29.16/2.32.6/2.33.7/2.34.1. Affected by this issue is some unknown functionality of the component Tailnet Coordinator. The manipulation of the argument AllowedIPs results in input validation. This vulnerability is known as CVE-2026-55428. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability classified as critical has been found in Coder up to 2.29.16/2.32.6/2.33.7/2.34.1. Affected is an unknown function of the component Tailnet Coordinator. The manipulation of the argument AllowedIPs with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-55428 since 06/16/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available.

Upgrading to version 2.29.17, 2.32.7, 2.33.8 or 2.34.2 eliminates this vulnerability.

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Productinfo

Name

• Coder

Version

• 2.29.0
• 2.29.1
• 2.29.2
• 2.29.3
• 2.29.4
• 2.29.5
• 2.29.6
• 2.29.7
• 2.29.8
• 2.29.9
• 2.29.10
• 2.29.11
• 2.29.12
• 2.29.13
• 2.29.14
• 2.29.15
• 2.29.16
• 2.32.0
• 2.32.1
• 2.32.2
• 2.32.3
• 2.32.4
• 2.32.5
• 2.32.6
• 2.33.0
• 2.33.1
• 2.33.2
• 2.33.3
• 2.33.4
• 2.33.5
• 2.33.6
• 2.33.7
• 2.34.0
• 2.34.1

Website

• Product: https://github.com/coder/coder/

CPE 2.3info

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CPE 2.2info

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