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    CVE-2026-21921

    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.

    Published:Jan 15, 2026
    Last Modified:Apr 18, 2026
    EPS:Jan 15, 2026
    EPSS Score:0.00018
    CVSS Score:6.5

    Affected Products

    Vendor
    Juniper
    Product
    Junos
    Vendor
    Juniper
    Product
    Junos Os Evolved
    Vendor
    Juniper Networks
    Product
    Junos Os
    Vendor
    Juniper Networks
    Product
    Junos Os Evolved

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-416 Use After Free

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

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    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High