{"id":"CVE-2021-27862","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-27862","generatedAt":"2026-10-27T21:19:39.658Z","title":"Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers).","description":"Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers).","published":"2022-09-27T19:15:09.000Z","lastModified":"2026-06-17T03:45:33.000Z","status":"Modified","sourceIdentifier":"cret@cert.org","cvss":{"version":"3.1","score":4.7,"severity":"MEDIUM","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N"},"cwe":["CWE-130","CWE-290"],"affected":["ieee/ieee 802.2","ietf/p802.1q"],"epss":{"score":0.00688,"percentile":0.52462,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.69%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://blog.champtar.fr/VLAN0_LLC_SNAP/","source":"cret@cert.org"},{"url":"https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/","tags":["Vendor Advisory"],"source":"cret@cert.org"},{"url":"https://kb.cert.org/vuls/id/855201","source":"cret@cert.org"},{"url":"https://standards.ieee.org/ieee/802.2/1048/","tags":["Vendor Advisory"],"source":"cret@cert.org"},{"url":"https://blog.champtar.fr/VLAN0_LLC_SNAP/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://kb.cert.org/vuls/id/855201","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://standards.ieee.org/ieee/802.2/1048/","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.kb.cert.org/vuls/id/855201","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-27862","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}