Rewterz Threat Advisory – Multiple Cisco Nexus Products Vulnerabilities

Severity

Medium

Analysis Summary

CVE-2021-27862 CVSS:4.7
Multiple Cisco Products could allow a remote attacker to bypass security restrictions, caused by improper validation of SNAP/LLC Ethernet frames. By sending a specially-crafted SNAP/LLC Ethernet header, an attacker could exploit this vulnerability to bypass layer 2 network filtering capabilities such as IPv6 RA guard.

CVE-2021-27861 CVSS:4.7
Multiple Cisco Products could allow a remote attacker to bypass security restrictions, caused by improper validation of SNAP/LLC Ethernet frames. By sending a specially-crafted SNAP/LLC Ethernet header, an attacker could exploit this vulnerability to bypass layer 2 network filtering capabilities such as IPv6 RA guard.

CVE-2021-27853 CVSS:4.7
Multiple Cisco Products could allow a remote attacker to bypass security restrictions, caused by a flaw in the processing of stacked Ethernet tag headers. By sending a specially-crafted request using a combination of VLAN 0 headers and LLC/SNAP headers, an attacker could exploit this vulnerability to bypass layer 2 network filtering capabilities such as IPv6 RA guard or ARP inspection.

Impact

Security Bypass

Indicators Of Compromise

CVE

• CVE-2022-20728
• CVE-2021-27854 

Affected Vendors

Cisco

Affected Products

• Cisco Nexus 3000 Series Switches
• Cisco Nexus 7000 Series Switches
• Cisco Nexus 5600 Platform Switches
• Cisco 350 Series Managed Switches

Remediation

Refer to Cisco Security Advisory for patch, upgrade or suggested workaround information. 
Cisco Security Advisory