CVE-2021-27854

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.

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CVSS v3.1

4.7 MEDIUM

EPSS

0.69%

probability of exploitation in 30 days

CISA KEV

Not listed

no confirmed exploitation reported

News coverage

sources referencing this CVE

EPSS Trend

Aug 16, 2026 → Sep 3, 2026

▲ 0.02pp

0.66% → 0.69% over 2 tracked changes

CVSS v3.1 Detail

Attack VectorADJACENT

Attack ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

ScopeCHANGED

ConfidentialityNONE

IntegrityLOW

AvailabilityNONE

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Connections

3 relationships

CWE-290

source

Timeline

disclosure → media coverage

Sep 27, 2022

Disclosure — published as a CVE record. · last revised by NVD Nov 4, 2025