{"cve":"CVE-2021-27861","nvd":{"published":"2022-09-27T19:15:09.330","modified":"2026-06-17T03:45:32.467","status":"Modified","description":"Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length (and optionally VLAN0 headers)","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","score":4.7},"cwes":["CWE-290","CWE-130"],"references":["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/"],"products":["ieee:ieee_802.2","ietf:p802.1q"],"source":"nvd","synced_at":"2026-10-19T21:36:05.460296998+00:00"},"epss":{"cve":"CVE-2021-27861","score":0.00663,"percentile":0.51724,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}