I had an issue with a device's SNMP items for which Zabbix couldn't retrieve the values (see ZBX-25592). This should have been fixed with version 7.0.8. So I updated to this version.

Afterwards the error didn't appear anymore. But it became even worse: The proxy now uses completely wrong SNMP values.
Since the update was the only change I had done, I reverted it by downgrading the proxy to the version which was in use before (7.0.6). Since then the values are correct again (of course except the issue which should have been fixed by the update).

Looking into the tcpdump capture the cause was easy to find:

1. Proxy requests 1.3.6.1.4.1.5491.10.1.5.3.1.3.3
2. SNMP agent responds with SNMP-USER-BASED-SM-MIB::usmStatsNotInTimeWindows.0 (1.3.6.1.6.3.15.1.1.2.0) = 117514
3. Proxy requests again 1.3.6.1.4.1.5491.10.1.5.3.1.3.3
4. SNMP agent responds with 1.3.6.1.4.1.5491.10.1.5.3.1.3.3 = 0 (correct value)

Even though the value of the first response doesn't match the requested OID Zabbix uses it as the item's value. Obviously this is totally wrong behaviour.

I attached the tcpdump capture to provide all the details. To decrypt it please use the following SNMPv3 credentials:

• User:   zabbix
• Authentication/Privacy:   SHA1/AES128
• Password:   zabbix123

Please fix this issue since it totally breaks our monitoring.