CVE-2026-55427: Coder vulnerable to SSH config injection via unsanitized server-supplied values in `coder config-ssh`

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.

Note: 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.