An Improper Preservation of Consistency Between Independent Representations of Shared State vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS allows a locally authenticated attacker with low privileges to cause a Denial of Service (DoS). If the device is very busy for example while executing a series of show commands on the CLI one or more SFPs might not be detected anymore. The system then changes its state to "unplugged" which is leading to traffic impact and at least a partial DoS. Once the system is less busy the port states return to their actual value. Indicators of compromise are log messages about unplugged SFPs and corresponding syspld messages without any physical or environmental cause. These can be checked by issuing the following commands: user@device# show log messages | match unplugged %PFE-6: fpc0 sfp-0/1/2 SFP unplugged %PFE-6: fpc0 sfp-0/1/3 SFP unplugged The following log messages will also be seen when this issue happens: fpc0 Error t…