In 3.12.11 it's even worse: now /var/log/hp and /var/log/hp/tmp are both world-writeable! That's really bad news. Any user can now e.g. delete files they don't own, etc.
Please don't use temporary directories for transferring files between different contexts. For the fax service, D-Bus is able to transfer files in method calls (by passing file descriptors) and this is a much better way of doing it than (a) writing to predictable filenames and risking symlink attacks, or (b) leaving world-writeable directories around tempting DoS attacks.