CVE-2021-27853

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    CVE-2021-27853

    Published: 27 Sept 2022Last Modified: 10 Mar 2026

    Summary:

    Details: Layer 2 network filtering capabilities such as IPv6 RA guard or ARP inspection can be bypassed using combinations of VLAN 0 headers and LLC/SNAP headers.

    References: https://www.kb.cert.org/vuls/id/855201, , https://kb.cert.org/vuls/id/855201, https://standards.ieee.org/ieee/802.1Q/10323/, https://standards.ieee.org/ieee/802.2/1048/, https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-VU855201-J3z8CKTX, https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/, https://blog.champtar.fr/VLAN0_LLC_SNAP/

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: N/A

    Events:

    Introduced- None
    Fixed -None

    Affected versions

    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