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CVE-2026-21921

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CVE-2026-21921

Published: Jan 15, 2026

Modified: Jan 15, 2026

PUBLISHED

CVSS v3.1

6.5

MEDIUM

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.

VendorProductVersions

Juniper Networks

Junos OS

affected
0 - < 22.4R3-S8
affected
23.2 - < 23.2R2-S5
affected
23.4 - < 23.4R2

Juniper Networks

Junos OS Evolved

affected
0 - < 22.4R3-S8-EVO
affected
23.2 - < 23.2R2-S5-EVO
affected
23.4 - < 23.4R2-EVO

Weaknesses (CWE)

CWE-416

CVSS v3.1 Details

CVSS v3.1 Vector

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

References

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