CVE-2021-27861

4.7 MEDIUM
Published: September 27, 2022 Modified: November 04, 2025

Description

Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length (and optionally VLAN0 headers)

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/
Source: cret@cert.org
Third Party Advisory
https://standards.ieee.org/ieee/802.1Q/10323/
Source: cret@cert.org
Third Party Advisory
https://standards.ieee.org/ieee/802.2/1048/
Source: cret@cert.org
Third Party Advisory
https://blog.champtar.fr/VLAN0_LLC_SNAP/
Source: af854a3a-2127-422b-91ae-364da2661108
https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://kb.cert.org/vuls/id/855201
Source: af854a3a-2127-422b-91ae-364da2661108
https://standards.ieee.org/ieee/802.1Q/10323/
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://standards.ieee.org/ieee/802.2/1048/
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://www.kb.cert.org/vuls/id/855201
Source: af854a3a-2127-422b-91ae-364da2661108

11 reference(s) from NVD

Quick Stats

CVSS v3 Score
4.7 / 10.0
EPSS (Exploit Probability)
0.1%
34th percentile
Exploitation Status
Not in CISA KEV

Affected Vendors

ieee ietf