Privileged crash-report disclosure via core-dump race

TOCTOU in Canonical Apport allows local users to expose privileged-process crash data through a core-dump creation race. During core-dump creation, Apport checks a process's current working directory separately from writing the dump, allowing a local user to change the directory between those operations. Low-privileged local access and successful race timing are required; the resulting report for a privileged process becomes readable by an unprivileged user.