Home/CVE/Layer 2 network filtering capabilities such as IPv6 RA guard or ARP inspection can be bypassed using combinations of VLA
CVE

CVE-2021-27853

Layer 2 network filtering capabilities such as IPv6 RA guard or ARP inspection can be bypassed using combinations of VLA

Layer 2 network filtering capabilities such as IPv6 RA guard or ARP inspection can be bypassed using combinations of VLAN 0 headers and LLC/SNAP headers.

MEDIUM · CVSS 4.7 EPSS 0.00109
Schedule remediation
  • Public exploit or PoC is available
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-290Authentication Bypass by Spoofing
CWE-290Authentication Bypass by Spoofing
▤

Affected Products & Versions

56
ieee 802.2<= 802.2h-1997
ietf p802.1q<= d1.0
cisco catalyst 6503-e firmwareall versions
cisco catalyst 6504-e firmwareall versions
cisco catalyst 6506-e firmwareall versions
cisco catalyst 6509-e firmwareall versions
cisco catalyst 6509-neb-a firmwareall versions
cisco catalyst 6509-v-e firmwareall versions
⚠

Public Exploits & PoCs

1
pocblog.champtar.fr · VLAN0_LLC_SNAPblog.champtar.fr
▣

Scoring & Timeline

4.7
MEDIUM · CVSS v3.1 · cret@cert.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD27 Sep 2022 · 06:15 PM
CVSS VectorCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

1
cisco-csafcisco-sa-VU855201-J3z8CKTX
🔗

References & Sources

6
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/Technical DescriptionThird Party Advisory
https://kb.cert.org/vuls/id/855201Third Party AdvisoryUS Government Resource
https://standards.ieee.org/ieee/802.1Q/10323/Vendor Advisory
https://standards.ieee.org/ieee/802.2/1048/Vendor Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-VU855201-J3z8CKTXThird Party Advisory
https://www.kb.cert.org/vuls/id/855201
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