AWS CLI SSO Device Code: Fix Broken Authentication
You’re SSH’d into a remote server or running AWS CLI in a Docker container, and suddenly aws configure sso fails with a cryptic localhost error. Sound familiar? You’re not alone. AWS recently changed their default SSO authentication flow, and it’s breaking workflows everywhere—especially for developers working in containerized environments or managing infrastructure remotely.
Here’s the thing: AWS introduced PKCE (Proof Key Code Exchange) as the new default authentication method in CLI version 2.22.0, thinking it would streamline the process. According to the official AWS CLI SSO documentation, this change provides enhanced security but creates new challenges for anyone not running the CLI and web browser on the same physical machine. The good news? There’s a simple one-flag fix that restores the reliable device code workflow you’re used to.
Why AWS CLI SSO Authentication Breaks
The Browser Localhost Problem
When you run aws configure sso with the new PKCE flow, here’s what happens behind the scenes:
- Step 1: AWS CLI generates a random TCP port (like 39171) and starts a local web server
- Step 2: Your browser gets redirected to
127.0.0.1:39171to complete authentication - Step 3: The browser can’t reach localhost because the CLI is running in a different environment
- Step 4: Authentication fails, and you’re stuck
This works perfectly when you’re running AWS CLI on your laptop with a local browser. But it completely breaks in these common scenarios:
| Environment | Why It Breaks | Impact |
|---|---|---|
| Docker Containers | CLI runs isolated from host browser | Can’t complete OAuth flow |
| Remote SSH Sessions | Browser and CLI on different machines | No localhost connection |
| CI/CD Pipelines | Headless environments without GUI browsers | No interactive authentication |
| WSL/VM Environments | Network isolation between environments | Port forwarding complexity |
The Technical Details: PKCE vs Device Code
According to the AWS CLI User Guide, AWS CLI version 2.22.0 introduced significant changes to SSO authentication methods:
PKCE (Proof Key Code Exchange) - New Default:
- Requires browser and CLI on same host
- Uses random localhost ports for OAuth callback
- More secure against certain attack vectors
- Designed for desktop/laptop development
Device Code Flow - Legacy Method:
- Browser-independent authentication
- Uses simple 8-character codes
- Works across network boundaries
- Perfect for remote/containerized workflows
The Simple Fix: Use Device Code Authentication
AWS has preserved the device code authentication method specifically for scenarios where PKCE doesn’t work. According to the official documentation, you can use the --use-device-code parameter to access the legacy authentication flow:
aws configure sso --use-device-code
That’s it. This single flag restores the familiar workflow where you:
- Get a simple URL and 8-character code
- Open the URL in any browser on any device
- Enter the code to complete authentication
- Return to your CLI session to continue
Version History and Migration Timeline
Understanding which AWS CLI version you’re running helps explain why authentication might have suddenly stopped working. According to the AWS CLI v2 changelog, version 2.22.0 introduced the OAuth 2.0 Authorization Code Flow with PKCE as the default for SSO login:
| Version | Release Date | Authentication Method | Notes |
|---|---|---|---|
| 2.21.x and earlier | Before March 2024 | Device code only | Original method |
| 2.22.0 | March 2024 | PKCE default, device code available with flag | Breaking change introduction |
| 2.24.x (current) | 2024-2025 | PKCE default, device code via --use-device-code | Latest stable |
Checking Your Version
aws --version
# Output: aws-cli/2.24.16 Python/3.11.6 Linux/5.4.0-1043-azure exe/x86_64.ubuntu.20
If you’re on version 2.22.0 or later and experiencing authentication issues, the --use-device-code flag is your solution.
Security Considerations
Device Code vs PKCE Security
Both authentication methods are secure when properly implemented:
Device Code Security Features:
- Time-limited codes (typically 15 minutes)
- One-time use codes
- Requires both URL access and code knowledge
- Audit trail in AWS CloudTrail
PKCE Security Advantages:
- Eliminates code interception risks
- Stronger cryptographic flow
- Reduced user interaction surface
For most development workflows, device code provides adequate security while maintaining usability across diverse environments.
Network Security Implications
Device code authentication requires outbound HTTPS access to AWS SSO endpoints. According to the AWS CLI SSO configuration guide, ensure your network security policies allow connections to:
https://device.sso.[region].amazonaws.com/- Your organization’s AWS SSO portal
Ensure your network security policies allow these connections.
Troubleshooting Common Issues
Problem: “Invalid device code” Error
Solution: Device codes expire quickly (usually 15 minutes). If you see this error:
- Generate a new code with
aws configure sso --use-device-code - Complete authentication within the time limit
- Ensure you’re entering the code exactly as displayed
Problem: Browser Opens But Shows Error
Solution: This often indicates network connectivity issues:
# Test connectivity to AWS SSO endpoint
curl -I https://device.sso.us-west-2.amazonaws.com/
# Check your AWS region configuration
aws configure list
Problem: Authentication Succeeds But Commands Fail
Solution: Verify your SSO session and region configuration:
# Check current authentication status
aws sts get-caller-identity
# List available SSO accounts/roles
aws configure list-profiles
# Switch to correct profile if needed
export AWS_PROFILE=your-sso-profile
Related Authentication and Infrastructure Articles
Understanding AWS CLI authentication fits into broader cloud security and infrastructure patterns:
- HashiCorp Vault vs AWS Secrets Manager vs Azure Key Vault - Compare secrets management solutions for multi-cloud environments
Conclusion
The AWS CLI’s move to PKCE authentication reflects a broader industry trend toward stronger security defaults. However, the one-size-fits-all approach doesn’t account for the diverse ways developers actually work with cloud infrastructure.
As documented in the official AWS CLI User Guide, the --use-device-code flag provides a simple, reliable solution for containerized and remote development workflows. While PKCE offers security advantages for local development, device code authentication remains the practical choice for many real-world scenarios.
As cloud development continues evolving toward containerized and remote-first approaches, tools must balance security with usability. For now, AWS CLI provides both options—use the one that fits your workflow.
Bottom line: If AWS CLI SSO authentication broke your workflow, add --use-device-code to your command and get back to building. Sometimes the simplest solutions are the best ones.