This is from
man 5 crontab:
Several environment variables are set up automatically by the cron(8)
daemon. SHELL is set to /bin/sh, and LOGNAME and HOME are set from the
/etc/passwd line of the crontab's owner. PATH is set to
"/usr/bin:/bin". HOME, SHELL, and PATH may be overridden by settings
in the crontab; LOGNAME is the user that the job is running from, and
may not be changed.
PATH is set by cron to
"/usr/bin:/bin". Now, to add more paths to the
PATH to be used by cron, just edit the crontab file (using
crontab -e command) and add, for example the following line somewhere at the beginning:
See also this Q&A from StackOverflow: crontab PATH and USER.