The Star program provides the ability to create and extract tar archives.
Robert Buchholz of the Gentoo Security team discovered a directory traversal vulnerability in the has_dotdot() function which does not identify //.. (slash slash dot dot) sequences in file names inside tar files.
By enticing a user to extract a specially crafted tar archive, a remote attacker could extract files to arbitrary locations outside of the specified directory with the permissions of the user running Star.
There is no known workaround at this time.
All Star users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=app-arch/star-1.5_alpha84"