A common setup to deploy to gh-pages on every commit via a CI system is to expose a github token to ENV and to use it directly in the auth part of the url. In module versions < 0.9.1 the auth portion of the url is outputted as part of the grunt tasks logging function. If this output is publicly available then the credentials should be considered compromised.

grunt-gh-pages before 0.10.0 may allow unencrypted GitHub credentials to be written to a log file