In tesseract 2.03 and 2.04, an attacker can rewrite an arbitrary user file by guessing the PID and creating a link to the user's file.
https://security-tracker.debian.org/tracker/CVE-2011-1136
https://euvd.enisa.europa.eu/vulnerability/EUVD-2011-1150
https://bugs.launchpad.net/ubuntu/+source/tesseract/+bug/607297