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01 Record

CVE-2021-27861

L2 network filtering bypass using stacked VLAN0 and LLC/SNAP headers with invalid lengths

MediumPUBLISHEDCNA: certcc
CNA base score4.7 CVSS v3.xCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
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02 Description

L2 network filtering bypass using stacked VLAN0 and LLC/SNAP headers with invalid lengths

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.66% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 51.1% of scored records. A rank, not a probability.
NVD base score
4.7 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2022-09-27 18:40Z4 YR AGO
Last updated
2025-11-04 19:12Z11 MO AGO
Reserved
2021-03-01
Assigning CNA
certcc
Record state
PUBLISHED
Severity
Medium (CVSS 4.7)
CNA CVSS vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Weaknesses
  • CWE-130Improper Handling of Length Parameter InconsistencyBase
  • CWE-290Authentication Bypass by SpoofingBase
Data version
5.2
Document digest
e2ba9b174712904db306af16c9f325b2c653d549106022ec8645fbf64ac0c44c

05 Affected products

VendorProductVersionsPlatforms
IEEE802.2802.2h-1997 to 802.2h-1997—
IETFdraft-ietf-v6ops-ra-guard08 to 08—
IETFP802.1QD1.0 to D1.0—

06 References