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    CVE-2021-34767

    A vulnerability in IPv6 traffic processing of Cisco IOS XE Wireless Controller Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, adjacent attacker to cause a Layer 2 (L2) loop in a configured VLAN, resulting in a denial of service (DoS) condition for that VLAN. The vulnerability is due to a logic error when processing specific link-local IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet that would flow inbound through the wired interface of an affected device. A successful exploit could allow the attacker to cause traffic drops in the affected VLAN, thus triggering the DoS condition.

    Published:Sep 23, 2021
    Last Modified:Oct 30, 2025
    EPS:Sep 23, 2021
    EPSS Score:0.001
    CVSS Score:7.4

    Affected Products

    Vendor
    Cisco
    Product
    Catalyst 9800
    Vendor
    Cisco
    Product
    Catalyst 9800-40
    Vendor
    Cisco
    Product
    Catalyst 9800-80
    Vendor
    Cisco
    Product
    Catalyst 9800-cl
    Vendor
    Cisco
    Product
    Catalyst 9800-l
    Vendor
    Cisco
    Product
    Catalyst 9800-l-c
    Vendor
    Cisco
    Product
    Catalyst 9800-l-f
    Vendor
    Cisco
    Product
    Catalyst 9800 Embedded Wireless Controller
    Vendor
    Cisco
    Product
    Ios Xe

    Exploits

    https://github.com/lukejenkins/CVE-2021-34767

    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