It was reported that hesiod unsafely checks EUID against UID in a few places to protect overriding certain configuration values with environment variables.

Vulnerable code:

configname = ((getuid() == geteuid()) && (getgid() == getegid()))
? getenv("HESIOD_CONFIG") : NULL;

If the process has elected to become full root, or dropped privileges while still possessing the file descriptor with additional privileges, or by some other way satisfies EUID == UID check without dropping all privileges, it can might allow privilege escalation for local attackers who are able to set the HESIOD_CONFIG or HES_DOMAIN environment variables and run affected SUID/SGUID binary.