A major vulnerability in CoreOS Linux Alpha has been patched, with the issue limited to versions 104x.0.0 of the distribution.
In the blog post Major Remote SSH Security Issue in CoreOS Linux Alpha, Subset of Users Affected the CoreOS Security Team described the issue saying:
A misconfiguration in the PAM subsystem in CoreOS Linux Alpha 1045.0.0 and 1047.0.0 allowed unauthorised users to gain access to accounts without a password or any other authentication token being required. This vulnerability affects a subset of machines running CoreOS Linux Alpha.
