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    CVE-2026-21920

    An Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If an SRX Series device configured for DNS processing, receives a specifically formatted DNS request flowd will crash and restart, which causes a service interruption until the process has recovered. This issue affects Junos OS on SRX Series: * 23.4 versions before 23.4R2-S5, * 24.2 versions before 24.2R2-S1, * 24.4 versions before 24.4R2. This issue does not affect Junos OS versions before 23.4R1.

    Published:Jan 15, 2026
    Last Modified:Apr 18, 2026
    EPS:Jan 15, 2026
    EPSS Score:0.00018
    CVSS Score:7.5

    Affected Products

    Vendor
    Juniper
    Product
    Junos
    Vendor
    Juniper
    Product
    Srx1500
    Vendor
    Juniper
    Product
    Srx1600
    Vendor
    Juniper
    Product
    Srx2300
    Vendor
    Juniper
    Product
    Srx300
    Vendor
    Juniper
    Product
    Srx320
    Vendor
    Juniper
    Product
    Srx340
    Vendor
    Juniper
    Product
    Srx345
    Vendor
    Juniper
    Product
    Srx380
    Vendor
    Juniper
    Product
    Srx4100
    Vendor
    Juniper
    Product
    Srx4120
    Vendor
    Juniper
    Product
    Srx4200
    Vendor
    Juniper
    Product
    Srx4300
    Vendor
    Juniper
    Product
    Srx4600
    Vendor
    Juniper
    Product
    Srx4700
    Vendor
    Juniper
    Product
    Srx5400
    Vendor
    Juniper
    Product
    Srx5600
    Vendor
    Juniper
    Product
    Srx5800
    Vendor
    Juniper Networks
    Product
    Junos Os

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-252 Unchecked Return Value

    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