CVE-2025-21595

/// Technical description

A Missing Release of Memory after Effective Lifetime vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker to cause an FPC to crash, leading to Denial of Service (DoS).

On all Junos OS and Junos OS Evolved platforms, in an EVPN-VXLAN scenario, when specific ARP packets are received on an IPv4 network, or specific NDP packets are received on an IPv6 network, kernel heap memory leaks, which eventually leads to an FPC crash and restart.

This issue does not affect MX Series platforms.

Heap size growth on FPC can be seen using below command.

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           45     3         0       2       2      2       32768      19       0 <<<<<<< Heap increase in all fPCs

This issue affects Jun

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References