Уязвимость программы systemd-tmpfiles демона Systemd, позволяющая нарушителю обойти существующие ограничения доступа и раскрыть защищаемую информацию

In systemd 223 through 235, a remote DNS server can respond with a custom crafted DNS NSEC resource record to trigger an infinite loop in the dns_packet_read_type_window() function of the 'systemd-resolved' service and cause a DoS of the affected service.

systemd-tmpfiles in systemd before 237 attempts to support ownership/permission changes on hardlinked files even if the fs.protected_hardlinks sysctl is turned off, which allows local users to bypass intended access restrictions via vectors involving a hard link to a file for which the user lacks write access, as demonstrated by changing the ownership of the /etc/passwd file.

It was discovered systemd does not correctly check the content of PIDFile files before using it to kill processes. When a service is run from an unprivileged user (e.g. User field set in the service file), a local attacker who is able to write to the PIDFile of the mentioned service may use this flaw to trick systemd into killing other services and/or privileged processes. Versions before v237 are vulnerable.