CVE-2017-9525

In the cron package through 3.0pl1-128 on Debian, and through 3.0pl1-128ubuntu2 on Ubuntu, the postinst maintainer script allows for group-crontab-to-root privilege escalation via symlink attacks against unsafe usage of the chown and chmod programs.

It was discovered that the postinst maintainer script in Cron unsafely handled file permissions during package install or update operations. An attacker could possibly use this issue to perform a privilege escalation attack. (CVE-2017-9525)

Florian Weimer discovered that Cron incorrectly handled certain memory operations during crontab file creation. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9704)

It was discovered that Cron incorrectly handled user input during crontab file creation. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9705)

It was discovered that Cron contained a use-after-free vulnerability in its force_rescan_user function. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9706)

USN-5259-1 fixed several vulnerabilities in Cron. This update provides the corresponding update for Ubuntu 18.04 LTS.

Original advisory details:

It was discovered that the postinst maintainer script in Cron unsafely handled file permissions during package install or update operations. An attacker could possibly use this issue to perform a privilege escalation attack. (CVE-2017-9525)

Florian Weimer discovered that Cron incorrectly handled certain memory operations during crontab file creation. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9704)

It was discovered that Cron incorrectly handled user input during crontab file creation. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9705)

It was discovered that Cron contained a use-after-free vulnerability in its force_rescan_user function. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9706)

USN-5259-1 and USN-5259-2 fixed vulnerabilities in Cron. Unfortunately that update was incomplete and could introduce a regression. This update fixes the problem.

We apologize for the inconvenience.

Original advisory details:

It was discovered that the postinst maintainer script in Cron unsafely handled file permissions during package install or update operations. An attacker could possibly use this issue to perform a privilege escalation attack. (CVE-2017-9525)

Florian Weimer discovered that Cron incorrectly handled certain memory operations during crontab file creation. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9704)

It was discovered that Cron incorrectly handled user input during crontab file creation. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9705)

It was discovered that Cron contained a use-after-free vulnerability in its force_rescan_user function. An attacker could possibly use this issue to cause a denial of service. (CVE-2019-9706)