Debian LTS: DLA-2801-1: cron security update
Summary
CVE-2017-9525
Fix group crontab to root escalation via postinst.
CVE-2019-9704
A very large crontab created by a user could crash the daemon.
CVE-2019-9705
Enforce maximum crontab line count of 10000 to prevent a malicious
user from creating an excessivly large crontab.
CVE-2019-9706
Fix for possible DoS by use-after-free.
Additionally, a bypass of /etc/cron.{allow,deny} on failure to open has
been fixed. If these files exist, then they must be readable by the user
executing crontab(1). Users will now be denied by default if they aren't.
For Debian 9 stretch, these problems have been fixed in version
3.0pl1-128+deb9u2.
We recommend that you upgrade your cron packages.
For the detailed security status of cron please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/source-package/cron
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS