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CVE-2021-27854

L2 network filtering bypass using stacked VLAN0, LLC/SNAP headers, and Ethernet to Wifi frame translation

Published: Sep 27, 2022Updated: Nov 4, 2025 Sources: CVE List NVDCWE-290
4.7MEDIUM
NVD MITRE
EPSS Score
0.7%
Top 51.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using combinations of VLAN 0 headers, LLC/SNAP headers, and converting frames from Ethernet to Wifi and its reverse.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:AAC:LPR:NUI:NS:CC:NI:LA:N
Exploitability
AV:AAttack Vector
Adjacent
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-290

Affected Products

IEEE
oss-project
ieee 802.2On-prem
Networking Infrastructure / dns-dhcp-ntp
802.2On-prem
Networking Infrastructure / dns-dhcp-ntp
IETF
oss-project
P802.1QOn-prem
Networking Infrastructure / dns-dhcp-ntp
draft-ietf-v6ops-ra-guardOn-prem
Networking Infrastructure / dns-dhcp-ntp
and 1 more affected products View all →

Exploitability

Official Patch Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique
Initial Access
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References

https://blog.champtar.fr/VLAN0_LLC_SNAP/
blog.champtar.fr
https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/
datatracker.ietf.org
https://kb.cert.org/vuls/id/855201
kb.cert.org
and 3 more references View all →

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