CVE intelligence and bounded remediation

CVE-2021-1228 — Cisco Nx-Os security vulnerability

High CVSS 7.4

A vulnerability in the fabric infrastructure VLAN connection establishment of Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) Mode could allow an unauthenticated, adjacent attacker to bypass security validations and connect an unauthorized server to the infrastructure VLAN. This vulnerability is due to insufficient security requirements during the Link Layer Discovery Protocol (LLDP) setup phase of the infrastructure VLAN. An attacker could exploit this vulnerability by sending a crafted LLDP packet on the adjacent subnet to an affected device. A successful exploit could allow the attacker to connect an unauthorized server to the infrastructure VLAN, which is highly privileged. With a connection to the infrastructure VLAN, the attacker can make unauthorized connections to Cisco Application Policy Infrastructure Controller (APIC) services or join other host endpoints.

Severity
High
CVSS
7.4 (3.1)
Published
2021-02-24
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-284

Affected products

  • cisco / nx-os / 11.0(1b)
  • cisco / nx-os / 11.0(1c)
  • cisco / nx-os / 11.0(1d)
  • cisco / nx-os / 11.0(1e)
  • cisco / nx-os / 11.0(2j)
  • cisco / nx-os / 11.0(2m)

Showing 6 representative product identities from 162 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

The detailed catalog view below loads this exact record, its source evidence, and the full seven-phase agentic change plan.