NVD

CVE-2026-21908 Detail

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.

Metrics

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.

CVSS 4.0 Severity and Vector Strings:

NIST: NVD

N/A

NVD assessment not yet provided.

Nist CVSS score does not match with CNA score

CNA: Juniper Networks, Inc.

CVSS-B 7.5 HIGH

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

CVSS 3.x Severity and Vector Strings:

CNA: Juniper Networks, Inc.

Base Score: 7.1 HIGH

Vector: CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS 2.0 Severity and Vector Strings:

National Institute of Standards and Technology

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://kb.juniper.net/JSA106007	Juniper Networks, Inc.	Vendor Advisory
https://supportportal.juniper.net/JSA106007	Juniper Networks, Inc.	Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-416	Use After Free	Juniper Networks, Inc.

Known Affected Software Configurations Switch to CPE 2.2

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Change History

2 change records found show changes

Initial Analysis by NIST 1/23/2026 2:40:42 PM

Action

Type

Old Value

New Value

Added

CPE Configuration

Record truncated, showing 2048 of 3169 characters.
View Entire Change Record

OR
          *cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.2:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.2:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:24.2:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:24.2:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:r2-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:r2-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:r2-s3:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.2:r1-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.2:r2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.4:r2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:r2-s3:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:r2-s4:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s3:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s4:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:r2-s4:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.2:r1-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.4:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.4:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.4:r1-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.4:r1-s3:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.2:r2-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.4:r2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:r2-s5:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:24.2:r2-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:25.2:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:25.2:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:25.2:r2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:25.2:r1-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.4:r2-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper

Added

Reference Type

Juniper Networks, Inc.: https://kb.juniper.net/JSA106007 Types: Vendor Advisory

Added

Reference Type

Juniper Networks, Inc.: https://supportportal.juniper.net/JSA106007 Types: Vendor Advisory

New CVE Received from Juniper Networks, Inc. 1/15/2026 4:16:06 PM

Action	Type	New Value
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.
Added	CVSS V4.0	AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:M/U:Green
Added	CVSS V3.1	AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Added	CWE	CWE-416
Added	Reference	https://kb.juniper.net/JSA106007
Added	Reference	https://supportportal.juniper.net/JSA106007

Quick Info

CVE Dictionary Entry:
CVE-2026-21908
NVD Published Date:
01/15/2026
NVD Last Modified:
01/23/2026
Source:
Juniper Networks, Inc.

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Information Technology Laboratory

National Vulnerability Database

National Vulnerability Database

CVE-2026-21908 Detail

Description

Metrics

References to Advisories, Solutions, and Tools

Weakness Enumeration

Known Affected Software Configurations Switch to CPE 2.2

CPEs loading, please wait.

Change History

Initial Analysis by NIST 1/23/2026 2:40:42 PM

New CVE Received from Juniper Networks, Inc. 1/15/2026 4:16:06 PM

Quick Info