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    CVE-2026-21903

    A Stack-based Buffer Overflow vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS allows a network-based attacker, authenticated with low privileges to cause a Denial-of-Service (DoS). Subscribing to telemetry sensors at scale causes all FPC connections to drop, resulting in an FPC crash and restart. The issue was not seen when YANG packages for the specific sensors were installed. This issue affects Junos OS:  * all versions before 22.4R3-S7, * 23.2 version before 23.2R2-S4, * 23.4 versions before 23.4R2.

    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 Networks
    Product
    Junos Os

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-121 Stack-based Buffer Overflow

    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