SRX Series: Antivirus updates are downloaded without verification
Juniper Networks Junos OS on SRX series devices do not verify the HTTPS server certificate before downloading anti-virus updates. This may allow a man-in-the-middle attacker to inject bogus signatures to cause service disruptions or make the device not detect certain types of attacks. Affected Junos OS releases are: 12.1X46 prior to 12.1X46-D71; 12.3X48 prior to 12.3X48-D55; 15.1X49 prior to 15.1X49-D110;
There are no viable workarounds for this issue.
It is good security practice to limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the device from trusted, administrative networks or hosts.