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    CVE-2026-21918

    A Double Free vulnerability in the flow processing daemon (flowd) of Juniper Networks Junos OS on SRX and MX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). On all SRX and MX Series platforms, when during TCP session establishment a specific sequence of packets is encountered a double free happens. This causes flowd to crash and the respective FPC to restart. This issue affects Junos OS on SRX and MX Series: * all versions before 22.4R3-S7, * 23.2 versions before 23.2R2-S3, * 23.4 versions before 23.4R2-S4, * 24.2 versions before 24.2R2.

    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
    Mx10004
    Vendor
    Juniper
    Product
    Mx10008
    Vendor
    Juniper
    Product
    Mx2008
    Vendor
    Juniper
    Product
    Mx2010
    Vendor
    Juniper
    Product
    Mx2020
    Vendor
    Juniper
    Product
    Mx204
    Vendor
    Juniper
    Product
    Mx240
    Vendor
    Juniper
    Product
    Mx304
    Vendor
    Juniper
    Product
    Mx480
    Vendor
    Juniper
    Product
    Mx960
    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-415 Double 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