An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS Evolved on PTX Series allows an unauthenticated, network-based attacker to cause impact to confidentiality and availability.

When an output firewall filter is configured with one or more terms where the action is 'reject', packets matching these terms are erroneously sent to the Routing Engine (RE) and further processed there. Processing of these packets will consume limited RE resources. Also responses from the RE back to the source of this traffic could reveal confidential information about the affected device.
This issue only applies to firewall filters applied to WAN or revenue interfaces, so not the mgmt or lo0 interface of the routing-engine, nor any input filters.

This issue affects Junos OS Evolved on PTX Series:

 

• all versions before 22.4R3-EVO,
• 23.2 versions before 23.2R2-EVO.

 

To be affected by this issue a configuration like the following needs to be present:

[ firewall family <family> filter <filter> term <term> then reject ]
[ interfaces <interface> unit <unit> family <family> filter output <filter> ]

The following software releases have been updated to resolve this specific issue: 22.4R3-EVO, 23.2R2-EVO, 23.4R1-EVO, and all subsequent releases.

 

This issue is being tracked as 1734892 which is visible on the Customer Support website.

 

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

To avoid this issue remove the affected reject action from the respective term(s) and replace it with discard, or add log or syslog actions.