Vulnerability Monitor

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CVE-2026-21908


A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root. The issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path. This issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled. This issue affects: Junos OS:  * from 23.2R2-S1 before 23.2R2-S5,  * from 23.4R2 before 23.4R2-S6,  * from 24.2 before 24.2R2-S3,  * from 24.4 before 24.4R2-S1,  * from 25.2 before 25.2R1-S2, 25.2R2;  Junos OS Evolved:  * from 23.2R2-S1 before 23.2R2-S5-EVO,  * from 23.4R2 before 23.4R2-S6-EVO,  * from 24.2 before 24.2R2-S3-EVO,  * from 24.4 before 24.4R2-S1-EVO,  * from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.


Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.1, indicating it requires adjacent network access but requires specific conditions to be met without requiring user interaction requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 2 products from juniper, from juniper organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2026-01-15T21:16:06.537

Last Modified

2026-01-23T19:40:42.420

Status

Analyzed

Source

[email protected]

Severity

CVSSv3.1: 7.1 (HIGH)

Weaknesses
  • Type: Primary
    CWE-416

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 25.2 Yes
Operating System juniper junos 25.2 Yes
Operating System juniper junos 25.2 Yes
Operating System juniper junos 25.2 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 24.2 Yes
Operating System juniper junos_os_evolved 24.2 Yes
Operating System juniper junos_os_evolved 24.2 Yes
Operating System juniper junos_os_evolved 24.2 Yes
Operating System juniper junos_os_evolved 24.2 Yes
Operating System juniper junos_os_evolved 24.2 Yes
Operating System juniper junos_os_evolved 24.4 Yes
Operating System juniper junos_os_evolved 24.4 Yes
Operating System juniper junos_os_evolved 24.4 Yes
Operating System juniper junos_os_evolved 24.4 Yes
Operating System juniper junos_os_evolved 24.4 Yes
Operating System juniper junos_os_evolved 25.2 Yes
Operating System juniper junos_os_evolved 25.2 Yes
Operating System juniper junos_os_evolved 25.2 Yes
Operating System juniper junos_os_evolved 25.2 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For juniper's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.