CVE-2026-102032 in Junos OS
Summary
by MITRE • 10/15/2026
A Missing Release of Memory after Effective Lifetime vulnerability in the l2ald process of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a denial of service via crafted packets when the static MAC-IP feature is in use.
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Analysis
by VulDB Data Team • 10/15/2026
The identified vulnerability represents a critical resource management flaw within the Layer 2 Address Resolution Protocol (ARP) handling mechanisms of Juniper Networks Junos OS and Junos OS Evolved operating systems. Specifically, this issue resides in the l2ald process, which is responsible for managing local layer two address resolution and neighbor discovery functions. The core technical deficiency involves a missing release of memory after effective lifetime, indicating that allocated heap or kernel memory buffers are not properly deallocated when they should be freed following their usage cycle. This type of error typically arises from logic errors in the code path where packet processing concludes without triggering the corresponding cleanup routines for dynamically allocated structures associated with ARP requests or replies.
An unauthenticated attacker positioned on an adjacent network segment can exploit this flaw by transmitting specially crafted packets that trigger the vulnerable memory allocation paths within the l2ald process. Because the vulnerability does not require authentication, it is particularly dangerous in environments where layer two connectivity exists between potentially hostile devices and Juniper infrastructure equipment such as switches or routers. The attacker needs only to send malformed ARP traffic designed to cause repeated allocations without subsequent deallocations. Over time, these unreleased memory blocks accumulate, leading to a gradual but inevitable exhaustion of available system resources.
The operational impact of this vulnerability is primarily a denial of service condition affecting the affected device and potentially adjacent network segments depending on how the operating system handles resource starvation. As memory consumption increases due to the failure to free allocated structures, the l2ald process may become unresponsive or crash entirely. Since ARP resolution is fundamental for layer two connectivity within an IP subnet, the disruption of this service can lead to a complete loss of communication for devices relying on that switch or router for MAC address translation. This effectively isolates network segments and halts normal data forwarding operations until the device is rebooted or the memory pressure subsides through other system interventions.
From a classification perspective, this vulnerability aligns with CWE-401, which describes Missing Release of Memory after Effective Lifetime. It also relates to CWE-789, as improper memory management can lead to broader stability issues and potential exploitation vectors if the corrupted state is manipulated further. In terms of adversary tactics, this scenario maps to MITRE ATT&CK technique T1499, Endpoint Denial of Service, where an attacker aims to degrade or disrupt services by exhausting system resources rather than compromising confidentiality or integrity directly.
Mitigation strategies for this vulnerability involve applying the vendor-provided software patches that address the memory management logic within the l2ald process. Administrators should ensure that all Juniper devices running affected versions of Junos OS and Junos OS Evolved are updated to the latest stable release containing the fix. In environments where immediate patching is not feasible, network segmentation can be employed to restrict layer two access from untrusted adjacent networks. Additionally, implementing strict ingress filtering on edge devices to drop malformed ARP packets before they reach the vulnerable process can provide a temporary compensating control while updates are deployed. Regular monitoring of system resource usage and logs for signs of memory leaks or service restarts is also recommended to detect potential exploitation attempts early.