Improper Link Resolution Before File Access ('Link Following')
crontab.c in crontab in FreeBSD and Apple Mac OS X allows local users to (1) determine the existence of arbitrary files via a symlink attack on a /tmp/crontab.XXXXXXXXXX temporary file and (2) perform MD5 checksum comparisons on arbitrary pairs of files via two symlink attacks on /tmp/crontab.XXXXXXXXXX temporary files.
CWE-59 - Improper Link Resolution Before File Access
'Improper link resolution before file access' occurs when software accesses a file resource but fails to verify that the file isn't a link or shortcut to another file. An attacker can potentially gain access to arbitrary files and from there the impact can vary, depending on the application, from sensitive data exposure to remote code execution.