In Sudo through 1.9.17p2 before 3e474c2, a failure of a setuid, setgid, or setgroups call, during...

In Sudo through 1.9.17p2 before 3e474c2, a failure of a setuid, setgid, or setgroups call, during a privilege drop before running the mailer, is not a fatal error and can lead to privilege escalation.