CVE-2025-21599

A Missing Release of Memory after Effective Lifetime vulnerability in the Juniper Tunnel Driver (jtd) of Juniper Networks Junos OS Evolved allows an unauthenticated network-based attacker to cause Denial of Service. 

Receipt of specifically malformed IPv6 packets, destined to the device, causes kernel memory to not be freed, resulting in memory exhaustion leading to a system crash and Denial of Service (DoS). Continuous receipt and processing of these packets will continue to exhaust kernel memory, creating a sustained Denial of Service (DoS) condition. This issue only affects systems configured with IPv6.

This issue affects Junos OS Evolved: 

• from 22.4-EVO before 22.4R3-S5-EVO, 
• from 23.2-EVO before 23.2R2-S2-EVO, 
• from 23.4-EVO before 23.4R2-S2-EVO, 
• from 24.2-EVO before 24.2R1-S2-EVO, 24.2R2-EVO.

This issue does not affect Juniper Networks Junos OS Evolved versions prior to 22.4R1-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/JSA92869