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.
Advisories

No advisories yet.

Fixes

Solution

The following software releases have been updated to resolve this specific issue: Junos OS 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S1, 25.2R1-S2, 25.2R2, 25.4R1, and all subsequent releases. Junos OS Evolved: 23.2R2-S5-EVO, 23.4R2-S6-EVO, 24.2R2-S3-EVO, 24.4R2-S1-EVO, 25.2R1-S2-EVO, 25.2R2-EVO, 25.4R1-EVO,


Workaround

There are no known workarounds for this issue.

History

Thu, 15 Jan 2026 21:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 15 Jan 2026 20:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Junos OS and Junos OS Evolved: Use after free vulnerability In 802.1X authentication daemon can cause crash of the dot1xd process
Weaknesses CWE-416
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 7.5, 'vector': 'CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/RE:M/U:Green'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: juniper

Published:

Updated: 2026-01-15T20:45:07.011Z

Reserved: 2026-01-05T17:32:48.710Z

Link: CVE-2026-21908

cve-icon Vulnrichment

Updated: 2026-01-15T20:45:01.036Z

cve-icon NVD

Status : Received

Published: 2026-01-15T21:16:06.537

Modified: 2026-01-15T21:16:06.537

Link: CVE-2026-21908

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses