Windows sandbox runner fails with CreateProcessAsUserW failed: 5 on Codex 26.609.4994.0 #28339

What version of Codex CLI is running?

OpenAI.Codex 26.609.4994.0

What subscription do you have?

Codex Pro 5x

Which model were you using?

gpt-5.5

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What terminal emulator and version are you using (if applicable)?

Windows Terminal

Codex doctor report

What issue are you seeing?

Sandboxed shell commands fail before PowerShell starts.

What steps can reproduce the bug?

Uploaded thread: 019ecbfd-1dc3-7352-9cb9-6c4f5dce5ef0

What is the expected behavior?

The command runs inside the sandbox.

Additional information

Diagnostics already checked:

• Rebooted Codex and Windows; issue persists.
• Same failure occurs in repo, home directory, and temp, so it is not workspace-specific.
• Repo ACL grants CodexSandboxUsers access.
• CodexSandboxUsers exists and contains CodexSandboxOffline and CodexSandboxOnline.
• Both sandbox accounts are active and members of Users.
• Security log shows CodexSandboxOffline successfully logs on, then immediately logs off.
• No visible sandbox-user process remains running.
• quser only shows the normal windows user console session.
• Commands work only when escalated outside the sandbox.