CVE-2025-21599

/// Technical description

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.

/// 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