CVE-2025-21595

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 Junos OS:

• All versions before 21.2R3-S7,
• 21.4 versions before 21.4R3-S4,
• 22.2 versions before 22.2R3-S1, 
• 22.3 versions before 22.3R3-S1, 
• 22.4 versions before 22.4R2-S2, 22.4R3.

and Junos OS Evolved:

• All versions before 21.2R3-S7-EVO,

• 21.4-EVO versions before 21.4R3-S4-EVO,

• 22.2-EVO versions before 22.2R3-S1-EVO, 

• 22.3-EVO versions before 22.3R3-S1-EVO, 

• 22.4-EVO versions before 22.4R3-EVO.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://supportportal.juniper.net/JSA96450