An Improper Handling of Exceptional Conditions vulnerability in the rpd-server of Juniper Networks Junos OS and Junos OS Evolved within cRPD allows an unauthenticated network-based attacker sending crafted TCP traffic to the routing engine (RE) to cause a CPU-based Denial of Service (DoS).

If specially crafted TCP traffic is received by the control plane, or a TCP session terminates unexpectedly, it will cause increased control plane CPU utilization by the rpd-server process.

While not explicitly required, the impact is more severe when RIB sharding is enabled.

Task accounting shows unexpected reads by the RPD Server jobs for shards:

user@junos> show task accounting detail
...
read:RPD Server.0.0.0.0+780.192.168.0.78+48886 TOT:00000003.00379787 MAX:00000000.00080516 RUNS: 233888\
read:RPD Server.0.0.0.0+780.192.168.0.78+49144 TOT:00000004.00007565 MAX:00000000.00080360 RUNS: 233888\
read:RPD Server.0.0.0.0+780.192.168.0.78+49694 TOT:00000003.00600584 MAX:00000000.00080463 RUNS: 233888\
read:RPD Server.0.0.0.0+780.192.168.0.78+50246 TOT:00000004.00346998 MAX:00000000.00080338 RUNS: 233888\

This issue affects:

Junos OS with cRPD: 

* All versions before 21.2R3-S8, 
* 21.4 before 21.4R3-S7, 
* 22.1 before 22.1R3-S6, 
* 22.2 before 22.2R3-S4, 
* 22.3 before 22.3R3-S3, 
* 22.4 before 22.4R3-S2, 
* 23.2 before 23.2R2-S2, 
* 24.2 before 24.2R2; 

Junos OS Evolved with cRPD: 

* All versions before 21.4R3-S7-EVO, 
* 22.2 before 22.2R3-S4-EVO, 
* 22.3 before 22.3R3-S3-EVO, 
* 22.4 before 22.4R3-S2-EVO, 
* 23.2 before 23.2R2-EVO.