CVE-2021-27861: Ieee 802.2

Medium severity, CVSS 4.7. EPSS: 0.7% chance of exploitation in the next 30 days.

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 products

• Ieee Ieee 802.2: up to and including 802.2h-1997
• IETF p802.1q: up to and including d1.0

Published 2022-09-27. Last modified 2026-06-17.