/usr/share/snmp/mibs/ is in libsnmp-base 5.7.3+dfsg-1.7+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/snmp/mibs/GNOME-SMI.txt
/usr/share/snmp/mibs/IANA-ADDRESS-FAMILY-NUMBERS-MIB.txt
/usr/share/snmp/mibs/IANA-LANGUAGE-MIB.txt
/usr/share/snmp/mibs/IANA-RTPROTO-MIB.txt
/usr/share/snmp/mibs/IANAifType-MIB.txt
/usr/share/snmp/mibs/LM-SENSORS-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-AGENT-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-EXAMPLES-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-EXTEND-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-MONITOR-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-PASS-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-PERIODIC-NOTIFY-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-SYSTEM-MIB.txt
/usr/share/snmp/mibs/NET-SNMP-TC.txt
/usr/share/snmp/mibs/NET-SNMP-VACM-MIB.txt
/usr/share/snmp/mibs/RFC-1215.txt
/usr/share/snmp/mibs/SNMP-TLS-TM-MIB.txt
/usr/share/snmp/mibs/SNMP-TSM-MIB.txt
/usr/share/snmp/mibs/UCD-DEMO-MIB.txt
/usr/share/snmp/mibs/UCD-DISKIO-MIB.txt
/usr/share/snmp/mibs/UCD-DLMOD-MIB.txt
/usr/share/snmp/mibs/UCD-IPFILTER-MIB.txt
/usr/share/snmp/mibs/UCD-IPFWACC-MIB.txt
/usr/share/snmp/mibs/UCD-SNMP-MIB-OLD.txt
/usr/share/snmp/mibs/UCD-SNMP-MIB.txt
/usr/share/snmp/mibs/miblist.txt