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CVE-2021-27862

14
FAUCET Score

CVE-2021-27862 describes a bypass vulnerability in Layer 2 network filtering, specifically IPv6 RA guard, affecting IEEE 802.2 and 802.1Q standards. This medium-severity vulnerability (CVSS 4.7) allows an attacker on the adjacent network to bypass security controls with low complexity, potentially leading to information disclosure or integrity issues. While there is no known active exploitation, public exploit code, or KEV listing, the vulnerability has garnered some community discussion and media coverage, indicating awareness within the cybersecurity community.

Impacted Technologies

VendorProductVersion(s)CPE
<= 802.2h-1997CPE matchmatch criteria
cpe:2.3:a:ieee:ieee_802.2:*:*:*:*:*:*:*:*
<= d1.0CPE matchmatch criteria
cpe:2.3:a:ietf:p802.1q:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.7MEDIUM

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

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.64%
Probability of exploitation in next 30 days
EPSS Percentile
47.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0064 is in the 74th percentile among its peer group of 1,802 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Advisories (1)

redhatCVE-2021-27862Moderate

Kernel: Layer 2 network filtering capabilities bypass Wifi frame conversion (and optionally VLAN0 headers)

Sep 29, 2022

References

kb.cert.org / vuls/id/855201
blog.champtar.fr / VLAN0_LLC_SNAP
datatracker.ietf.org / doc/draft-ietf-v6ops-ra-guard/08
Vendor Advisory
kb.cert.org / vuls/id/855201
standards.ieee.org / ieee/802.2/1048
Vendor Advisory