NVD

CVE-2026-21921 Detail

Description

A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS). When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered. This issue affects: Junos OS: * all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2; Junos OS Evolved: * all versions before 22.4R3-S8-EVO, * 23.2 versions before 23.2R2-S5-EVO, * 23.4 versions before 23.4R2-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 7.1 HIGH

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M

CVSS 3.x Severity and Vector Strings:

CNA: Juniper Networks, Inc.

Base Score: 6.5 MEDIUM

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/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/JSA106021	Juniper Networks, Inc.	Vendor Advisory
https://supportportal.juniper.net/JSA106021	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 1:52:35 PM

Action

Type

Old Value

New Value

Added

CPE Configuration

Record truncated, showing 2048 of 3675 characters.
View Entire Change Record

OR
          *cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:r2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:22.4:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:22.4:r1-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:22.4:r1-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:22.4:r2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:r3:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.2:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.2:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:r2-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:r2-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:22.4:r2-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:22.4:r2-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:22.4:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s2:*:*:*:*:*:*
          *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_os_evolved:22.4:r3:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:r3-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:22.4:r3-s2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:*
          *cpe:2.3:o:juniper:junos_os_evolved:23.4:r1-s1:*:*:*:*:*:*
          *cpe:2

Added

Reference Type

Juniper Networks, Inc.: https://kb.juniper.net/JSA106021 Types: Vendor Advisory

Added

Reference Type

Juniper Networks, Inc.: https://supportportal.juniper.net/JSA106021 Types: Vendor Advisory

New CVE Received from Juniper Networks, Inc. 1/15/2026 4:16:08 PM

Action	Type	New Value
Added	Description	A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS). When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered. This issue affects: Junos OS: * all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2; Junos OS Evolved: * all versions before 22.4R3-S8-EVO, * 23.2 versions before 23.2R2-S5-EVO, * 23.4 versions before 23.4R2-EVO.
Added	CVSS V4.0	AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/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:Y/R:A/V:X/RE:M/U:X
Added	CVSS V3.1	AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Added	CWE	CWE-416
Added	Reference	https://kb.juniper.net/JSA106021
Added	Reference	https://supportportal.juniper.net/JSA106021

Quick Info

CVE Dictionary Entry:
CVE-2026-21921
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-2026-21921 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 1:52:35 PM

New CVE Received from Juniper Networks, Inc. 1/15/2026 4:16:08 PM

Quick Info