CVE-2026-102015 in Junos OS
Summary
by MITRE • 10/14/2026
A Heap-based Buffer Overflow vulnerability in the secure-dot1xd process of Juniper Networks on Junos OS and Junos OS Evolved allows an unauthenticated adjacent network attacker to execute code as root or cause a denial of service via an EAPOL frame sent to an 802.1X-authenticated interface.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified in the secure-dot1xd process within Juniper Networks' Junos OS and Junos OS Evolved represents a critical security flaw rooted in improper memory management during the processing of Extensible Authentication Protocol over LAN (EAPOL) frames. This heap-based buffer overflow occurs when the daemon fails to adequately validate the length or structure of incoming authentication packets before copying them into allocated memory buffers. The secure-dot1xd process is responsible for handling 802.1X network access control, which authenticates devices attempting to connect to a protected network segment. Because this service operates with high privileges and handles sensitive authentication data, any compromise of its integrity directly impacts the security posture of the entire infrastructure.
An unauthenticated attacker positioned on the same local area network segment can exploit this flaw by crafting malicious EAPOL frames that contain oversized or malformed fields. When these packets are sent to an interface configured for 802.1X authentication, the secure-dot1xd process attempts to parse and store the data without sufficient bounds checking. This oversight allows the attacker to write beyond the boundaries of the allocated heap memory, overwriting adjacent memory structures such as function pointers or metadata used by the allocator. The specific nature of this overflow enables two distinct attack vectors: arbitrary code execution with root-level privileges or a denial of service condition.
The impact of successful exploitation is severe due to the privilege level at which the vulnerable process operates. If an attacker successfully manipulates memory control structures, they can redirect program flow to execute malicious shellcode injected into the heap space. This results in full system compromise as the code executes with root privileges, granting the attacker unrestricted access to the operating system and all connected network resources. Alternatively, if the overflow corrupts critical data without leading to code execution, it causes a crash of the secure-dot1xd process or potentially the entire device, resulting in a denial of service that disrupts network connectivity for legitimate users relying on 802.1X authentication services.
From a classification perspective, this vulnerability aligns with CWE-122, which describes heap-based buffer overflow conditions where data is written beyond the allocated memory region. The attack vector falls under ATT&CK technique T1059, specifically involving command-line interface or script execution following initial access via network service exploitation. Furthermore, because it requires an adjacent attacker to send crafted packets without prior authentication, it exemplifies CWE-287, which covers improper authentication mechanisms that fail to verify identity before processing sensitive inputs.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is the application of vendor-provided software updates or patches that address the memory validation logic within the secure-dot1xd process. Network administrators should ensure that all Junos OS and Junos OS Evolved systems are updated to versions where this heap overflow has been corrected. In environments where immediate patching is not feasible, implementing strict network segmentation can limit exposure by preventing untrusted devices from reaching 802.1X-enabled interfaces directly. Additionally, deploying intrusion detection or prevention systems capable of inspecting EAPOL traffic for anomalous packet sizes may provide an additional layer of defense against exploitation attempts while patches are being deployed.