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
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.4$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Cisco IOS, IOS XE, Meraki, NX-OS and Small Business Switch. Affected is an unknown function of the component IPv6 RA Guard. The manipulation leads to authentication spoofing. This vulnerability is traded as CVE-2021-27862. The attack can only be done within the local network. There is no exploit available. It is recommended to upgrade the affected component. If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Cisco IOS, IOS XE, Meraki, NX-OS and Small Business Switch (Router Operating System). This issue affects an unknown function of the component IPv6 RA Guard. The manipulation with an unknown input leads to a authentication spoofing vulnerability. Using CWE to declare the problem leads to CWE-290. This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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

The weakness was disclosed 09/28/2022 as cisco-sa-VU855201-J3z8CKTX. The advisory is shared at tools.cisco.com. The identification of this vulnerability is CVE-2021-27862 since 03/01/2021. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/21/2025).

Upgrading eliminates this vulnerability.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

Vendor

Name

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

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: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

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

Local: No
Remote: Partially

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Timelineinfo

03/01/2021 🔍
09/28/2022 +575 days 🔍
09/28/2022 +0 days 🔍
05/21/2025 +966 days 🔍

Sourcesinfo

Vendor: cisco.com

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

CVE: CVE-2021-27862 (🔍)
GCVE (CVE): GCVE-0-2021-27862
GCVE (VulDB): GCVE-100-209657
scip Labs: https://www.scip.ch/en/?labs.20150108

Entryinfo

Created: 09/28/2022 07:06
Updated: 05/21/2025 20:03
Changes: 09/28/2022 07:06 (40), 10/24/2022 15:47 (11), 05/21/2025 20:03 (15)
Complete: 🔍
Cache ID: 216:362:103

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