CVE-2024-47502: Junos OS Evolved: TCP session state is not always cleared on the Routing Engine leading to DoS

An Allocation of Resources Without Limits or Throttling vulnerability in the kernel of Juniper Networks Junos OS Evolved allows an unauthenticated, network based attacker to cause a Denial of Service (DoS).

In specific cases the state of TCP sessions that are terminated is not cleared, which over time leads to an exhaustion of resources, preventing new connections to the control plane from being established.

A continuously increasing number of connections shown by:

user@host > show system connections

is indicative of the problem. To recover the respective RE needs to be restarted manually.

This issue only affects IPv4 but does not affect IPv6. This issue only affects TCP sessions established in-band (over an interface on an FPC) but not out-of-band (over the management ethernet port on the routing-engine).

This issue affects Junos OS Evolved:

All versions before 21.4R3-S9-EVO, 22.2 versions before 22.2R3-S4-EVO, 22.4 version before 22.4R3-S3-EVO, 23.2 versions before 23.2R2-S1-EVO, 23.4 versions before 23.4R2-EVO.