CVE-2021-27862
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).
Does this matter?
Lower severity and a low EPSS score (0.69%). Track it; it rarely justifies an emergency change on its own.
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).
- CVSS 3.1
- 4.7 MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
- EPSS
- 0.69% probability · 52th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-130, CWE-290
- Affected
- ieee/ieee 802.2 · ietf/p802.1q
- Source
- cret@cert.org
EPSS 0.7% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://blog.champtar.fr/VLAN0_LLC_SNAP/
- https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/Vendor Advisory
- https://kb.cert.org/vuls/id/855201
- https://standards.ieee.org/ieee/802.2/1048/Vendor Advisory
- https://blog.champtar.fr/VLAN0_LLC_SNAP/
- https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/Vendor Advisory
- https://kb.cert.org/vuls/id/855201
- https://standards.ieee.org/ieee/802.2/1048/Vendor Advisory
- https://www.kb.cert.org/vuls/id/855201
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.