A Missing Release of Memory after Effective Lifetime vulnerability in the Packet Forwarding Engine (PFE) of the Juniper Networks Junos OS on the MX Series platforms with Trio-based FPCs allows an unauthenticated, adjacent attacker to cause a Denial of Service (DoS).

In case of channelized Modular Interface Cards (MICs), every physical interface flap operation will leak heap memory. Over a period of time, continuous physical interface flap operations causes local FPC to eventually run out of memory and crash.  

Below CLI command can be used to check the memory usage over a period of time:

user@host> show chassis fpc

                Temp CPU Utilization (%)   CPU Utilization (%) Memory  
Utilization (%)
  Slot State     (C)  Total  Interrupt     1min   5min  
15min DRAM (MB) Heap     Buffer

  0
Online       43     41        
2                           2048       49         14

  1
Online       43     41        
2                          
2048       49         14

  2
Online       43     41        
2                          
2048       49         14

This issue affects Junos OS on MX Series: 

* All versions before 21.2R3-S7, 
* from 21.4 before 21.4R3-S6, 
* from 22.1 before 22.1R3-S5, 
* from 22.2 before 22.2R3-S3, 
* from 22.3 before 22.3R3-S2, 
* from 22.4 before 22.4R3, 
* from 23.2 before 23.2R2, 
* from 23.4 before 23.4R2.