Cisco IOS/IOS XE/Meraki/NX-OS/Small Business Switch IPv6 RA Guard authentication spoofing

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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A vulnerability classified as critical has been found in Cisco IOS, IOS XE, Meraki, NX-OS and Small Business Switch (Router Operating System). This affects an unknown code block of the component IPv6 RA Guard. The manipulation with an unknown input leads to a authentication spoofing vulnerability. CWE is classifying the issue as CWE-290. This attack-focused weakness is caused by improperly implemented authentication schemes that are subject to spoofing attacks. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using combinations of VLAN 0 headers, LLC/SNAP headers, and converting frames from Ethernet to Wifi and its reverse.

The weakness was published 09/28/2022 as cisco-sa-VU855201-J3z8CKTX. It is possible to read the advisory at This vulnerability is uniquely identified as CVE-2021-27854 since 03/01/2021. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/24/2022).

Upgrading eliminates this vulnerability.






  • commercial

CPE 2.3info

CPE 2.2info


VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.4

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.7
NVD Vector: 🔒



VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍


Class: Authentication spoofing
CWE: CWE-290 / CWE-287
ATT&CK: Unknown

Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒


Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍


Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒


03/01/2021 CVE reserved
09/28/2022 +575 days Advisory disclosed
09/28/2022 +0 days VulDB entry created
10/24/2022 +26 days VulDB last update



Advisory: cisco-sa-VU855201-J3z8CKTX
Status: Confirmed

CVE: CVE-2021-27854 (🔒)
scip Labs:


Created: 09/28/2022 07:04 AM
Updated: 10/24/2022 03:35 PM
Changes: 09/28/2022 07:04 AM (40), 10/24/2022 03:35 PM (11)
Complete: 🔍


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