CVE-2021-27854

NameCVE-2021-27854
DescriptionLayer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using combinations of VLAN 0 headers, LLC/SNAP headers, and converting frames from Ethernet to Wifi and its reverse.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub advisories/code/issues, web search, more)

Notes

https://kb.cert.org/vuls/id/855201
https://blog.champtar.fr/VLAN0_LLC_SNAP/
Linux kernel behaves as expected, it's the user space responsibility to build
correct filtering rules.

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