Log Message:
Security fix for CAN-2005-2945 and CAN-2005-2992:

"arc 5.21j and earlier create temporary files with world-readable permissions,
which allows local users to read sensitive information from files created by
arc or marc."

http://www.zataz.net/adviso/arc-09052005.txt
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2945

Patch from Debian.