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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.

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