Junos OS Evolved: When a control-plane firewall filter refers to a prefix-list with more than 10 entries it's not matching

Summary

A Use of Incorrect Operator vulnerability in the Routing Engine firewall of Juniper Networks Junos OS Evolved allows an unauthenticated, network-based attacker to bypass security restrictions. When a firewall filter which is applied to the lo0 or re:mgmt interface references a prefix list with 'from prefix-list', and that prefix list contains more than 10 entries, the prefix list doesn't match and packets destined to or from the local device are not filtered. This issue affects firewall filters applied to the re:mgmt interfaces as input and output, but only affects firewall filters applied to the lo0 interface as output. This issue is applicable to IPv4 and IPv6 as a prefix list can contain IPv4 and IPv6 prefixes. This issue affects Junos OS Evolved: • 23.2R2-S3-EVO versions before 23.2R2-S4-EVO, • 23.4R2-S3-EVO versions before 23.4R2-S5-EVO, • 24.2R2-EVO versions before 24.2R2-S1-EVO, • 24.4-EVO versions before 24.4R1-S3-EVO, 24.4R2-EVO. This issue doesn't affect Junos OS Evolved versions before 23.2R1-EVO.

Timeline

1. Jul 11, 2025, 3:09 PM UTCCVE published
2. Jul 11, 2025, 4:04 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Jul 18, 2025, 7:16 AM UTCRecord last updated

Affected versions

• Juniper Networks Junos OS Evolved

  From 23.2R2-S3-EVO · fixed in 23.2R2-S4-EVO; From 23.4R2-S3-EVO · fixed in 23.4R2-S5-EVO; From 24.2R2-EVO · fixed in 24.2R2-S1-EVO

References 1