CVE-2021-27853 – L2 network filtering can be bypassed using stacked VLAN0 and LLC/SNAP headers

https://notcve.org/view.php?id=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. Las capacidades de filtrado de la red de capa 2, como la protección IPv6 RA o la inspección ARP, pueden omitirse usando combinaciones de encabezados VLAN 0 y encabezados LLC/SNAP • https://blog.champtar.fr/VLAN0_LLC_SNAP https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08 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 • CWE-290: Authentication Bypass by Spoofing •