Exposure of SSH credentials in Rancher/Fleet

Summary

### Impact This vulnerability only affects customers using Fleet for continuous delivery with authenticated Git and/or Helm repositories.

A security vulnerability ([CVE-2022-29810](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-29810)) was discovered in `go-getter` library in versions prior to [`v1.5.11`](https://github.com/hashicorp/go-getter/releases/tag/v1.5.11) that exposes SSH private keys in base64 format due to a failure in redacting such information from error messages. The vulnerable version of this library is used in Rancher through Fleet in versions of Fleet prior to [`v0.3.9`](https://github.com/rancher/fleet/releases/tag/v0.3.9). This issue affects Rancher versions 2.5.0 up to and including 2.5.12 and from 2.6.0 up to and including 2.6.3.

When Git and/or Helm authentication is configured in [Fleet](https://rancher.com/docs/rancher/v2.6/en/deploy-across-clusters/fleet/) and Fleet is used to deploy a git repo through `Continuous Delivery`, the affected `go-getter` version will expose the configured SSH private key secret if Fleet fails to download the git repo due to a misconfigured URL. The exposed SSH key is logged in base64 format as a query parameter together with the git URL. The credentials can be seen in Rancher UI and in Fleet's deployment pod logs.

### Patches Patched versions include releases 2.5.13, 2.6.4 and later versions.

### Workarounds There is not a direct mitigation besides upgrading to the patched Rancher versions. Until you are able to upgrade, limit access in Rancher to trusted users and carefully validate the URLs you are using are correct. Please note that the SSH key might still be compromised in valid URLs if the service goes down or a connection error happens when pulling from the repos.

**Note:** If you believe that SSH keys might have been exposed in your environment, it's highly advised to rotate them.

### Credits This issue was found and reported by Dagan Henderson from Raft Engineering.

### For more information If you have any questions or comments about this advisory: * Reach out to [SUSE Rancher Security team](https://github.com/rancher/rancher/security/policy) for security related inquiries. * Open an issue in [Rancher](https://github.com/rancher/rancher/issues/new/choose) repository. * Verify our [support matrix](https://www.suse.com/suse-rancher/support-matrix/all-supported-versions/) and [product support lifecycle](https://www.suse.com/lifecycle/).