{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"state":"PUBLISHED","cveId":"CVE-2021-27861","assignerOrgId":"37e5125f-f79b-445b-8fad-9564f167944b","assignerShortName":"certcc","datePublished":"2022-09-27T18:40:13.742Z","dateUpdated":"2025-11-04T19:12:27.712Z","dateReserved":"2021-03-01T00:00:00.000Z"},"containers":{"cna":{"title":"L2 network filtering bypass using stacked VLAN0 and LLC/SNAP headers with invalid lengths","datePublic":"2022-09-27T00:00:00.000Z","providerMetadata":{"orgId":"37e5125f-f79b-445b-8fad-9564f167944b","shortName":"certcc","dateUpdated":"2022-10-12T00:00:00.000Z"},"descriptions":[{"lang":"en","value":"Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length (and optionally VLAN0 headers)"}],"affected":[{"vendor":"IEEE","product":"802.2","versions":[{"version":"802.2h-1997","status":"affected","lessThanOrEqual":"802.2h-1997","versionType":"custom"}]},{"vendor":"IETF","product":"draft-ietf-v6ops-ra-guard","versions":[{"version":"08","status":"affected","lessThanOrEqual":"08","versionType":"custom"}]},{"vendor":"IETF","product":"P802.1Q","versions":[{"version":"D1.0","status":"affected","lessThanOrEqual":"D1.0","versionType":"custom"}]}],"references":[{"url":"https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/"},{"url":"https://standards.ieee.org/ieee/802.2/1048/"},{"url":"https://standards.ieee.org/ieee/802.1Q/10323/"},{"url":"https://kb.cert.org/vuls/id/855201"},{"url":"https://blog.champtar.fr/VLAN0_LLC_SNAP/"}],"credits":[{"lang":"en","value":"Etienne Champetier (@champtar) <champetier.etienne@gmail.com>"}],"problemTypes":[{"descriptions":[{"type":"CWE","lang":"en","description":"CWE-130 Improper Handling of Length Parameter","cweId":"CWE-130"}]},{"descriptions":[{"type":"CWE","lang":"en","description":"CWE-290: Authentication Bypass by Spoofing","cweId":"CWE-290"}]}],"source":{"discovery":"EXTERNAL"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/","tags":["x_transferred"]},{"url":"https://standards.ieee.org/ieee/802.2/1048/","tags":["x_transferred"]},{"url":"https://standards.ieee.org/ieee/802.1Q/10323/","tags":["x_transferred"]},{"url":"https://kb.cert.org/vuls/id/855201","tags":["x_transferred"]},{"url":"https://blog.champtar.fr/VLAN0_LLC_SNAP/","tags":["x_transferred"]},{"url":"https://www.kb.cert.org/vuls/id/855201"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2025-11-04T19:12:27.712Z"}},{"metrics":[{"cvssV3_1":{"scope":"CHANGED","version":"3.1","baseScore":4.7,"attackVector":"ADJACENT_NETWORK","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","integrityImpact":"LOW","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"NONE","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2025-05-21T15:06:05.203947Z","id":"CVE-2021-27861","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2025-05-21T15:06:11.048Z"}}]}}