// For flags

CVE-2021-27861

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

Severity Score

4.7
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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

Las capacidades de filtrado de red de capa 2, como la protección RA de IPv6, pueden omitirse usando encabezados LLC/SNAP con una longitud no válida (y, opcionalmente, encabezados VLAN0)

*Credits: Etienne Champetier (@champtar) <champetier.etienne@gmail.com>
CVSS Scores
Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-03-01 CVE Reserved
  • 2022-09-27 CVE Published
  • 2024-04-19 EPSS Updated
  • 2024-09-16 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-130: Improper Handling of Length Parameter Inconsistency
  • CWE-290: Authentication Bypass by Spoofing
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Ieee
Search vendor "Ieee"
 Ieee 802.2
Search vendor "Ieee" for product "Ieee 802.2"
 <= 802.2h-1997
Search vendor "Ieee" for product "Ieee 802.2" and version " <= 802.2h-1997"
-
Affected
Ietf
Search vendor "Ietf"
 P802.1q
Search vendor "Ietf" for product "P802.1q"
 <= d1.0
Search vendor "Ietf" for product "P802.1q" and version " <= d1.0"
-
Affected