Coder up to 2.29.16/2.32.6/2.33.7/2.34.1 SSH Config HostnameSuffix/SSHConfigOptions injection

Summaryinfo

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 by this vulnerability is an unknown functionality of the component SSH Config Handler. The manipulation of the argument HostnameSuffix/SSHConfigOptions leads to injection. This vulnerability is traded as CVE-2026-55427. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Coder up to 2.29.16/2.32.6/2.33.7/2.34.1. It has been rated as critical. This issue affects some unknown processing of the component SSH Config Handler. The manipulation of the argument HostnameSuffix/SSHConfigOptions with an unknown input leads to a injection vulnerability. Using CWE to declare the problem leads to CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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, `coder config-ssh` wrote server-supplied SSH settings (`HostnameSuffix`, `SSHConfigOptions`) into the user's `~/.ssh/config` without sanitizing embedded newlines or restricting directives so a malicious or compromised Coder server could inject arbitrary SSH configuration. Practical exploitation requires control of the server-supplied values through a malicious or compromised deployment, a man-in-the-middle position or admin access to the `HostnameSuffix` and `SSHConfigOptions` settings. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 validates `HostnameSuffix` and `SSHConfigOptions` against a strict character set that rejects newlines and other control characters. As a workaround, inspect `coder config-ssh --dry-run` output before applying changes.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-55427 since 06/16/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1055 according to MITRE ATT&CK.

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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