The issue exists in the way sudo has implemented running commands with an arbitrary user ID in versions earlier than 1.8.28. The CVSS v3 score is 7.8, so we are talking about a high severity vulnerability, easy to exploit, although the attack vector is local and requires a non-default configuration.
Invoking sudo with -u#-1 or -u#4294967295 specified in the sudo command, the malicious user can run arbitrary commands as root, as long as the sudoers meets the previously described conditions.
In addition to that, the malicious sudo operation will not log correctly through the syslog facility. It supposed to be logged as root, however, it turned out to be -1 or 4294967295.
You can read more info about this CVE: