It has been discovered, that cpio, a program to manage archives of
files, creates output files with -O and -F with broken permissions due
to a reset zero umask which allows local users to read or overwrite
those files.
For the stable distribution (woody) this problem has been fixed in
version 2.4.2-39woody1.
For the unstable distribution (sid) this problem will be fixed soon.
We recommend that you upgrade your cpio package.