CVE-2021-27853

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.

• CWE-290
• CWE-290

• https://blog.champtar.fr/VLAN0_LLC_SNAP/Exploit, Third Party Advisory
• https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/Technical Description, Third Party Advisory
• https://kb.cert.org/vuls/id/855201Third Party Advisory, US Government Resource
• https://standards.ieee.org/ieee/802.1Q/10323/Vendor Advisory
• https://standards.ieee.org/ieee/802.2/1048/Vendor Advisory
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-VU855201-J3z8CKTXThird Party Advisory
• https://blog.champtar.fr/VLAN0_LLC_SNAP/Exploit, Third Party Advisory
• https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/Technical Description, Third Party Advisory
• https://kb.cert.org/vuls/id/855201Third Party Advisory, US Government Resource
• https://standards.ieee.org/ieee/802.1Q/10323/Vendor Advisory
• https://standards.ieee.org/ieee/802.2/1048/Vendor Advisory
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-VU855201-J3z8CKTXThird Party Advisory
• https://www.kb.cert.org/vuls/id/855201

Published

Sep 27, 2022

Last Modified

Jun 17, 2026

Status

Modified

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