CVE-2021-47160 is a vulnerability identified in the Linux kernel's handling of VLAN (Virtual Local Area Network) traffic filtering within the Distributed Switch Architecture (DSA) driver for the mt7530 switch chip. The issue arises due to improper management of the PCR_MATRIX field, which is used to control VLAN traffic filtering behavior. Specifically, when VLAN filtering is enabled on bridge interfaces, the PCR_MATRIX field is set to all 1's, effectively allowing all VLAN traffic. However, when VLAN filtering is subsequently disabled, the PCR_MATRIX field is not reset accordingly. This oversight causes VLAN traffic to leak between bridge interfaces that should be isolated, violating network segmentation and potentially exposing sensitive data or allowing unauthorized network access. The vulnerability manifests in scenarios where multiple bridge interfaces with VLAN filtering are created and then disabled, as demonstrated by the sequence of commands in the description. The root cause is a redundant write to PCR_MATRIX in the mt7530_port_set_vlan_aware function, which conflicts with proper setup done in port_bridge_add and port_bridge_del functions. The fix involves removing this redundant write to ensure PCR_MATRIX is correctly managed and traffic isolation is maintained. This vulnerability affects Linux kernel versions containing the specified commit hashes, which correspond to affected mt7530 DSA driver implementations. Although no known exploits are reported in the wild, the flaw can lead to VLAN traffic leakage, undermining network segmentation and security policies in environments relying on Linux bridges and VLAN filtering with mt7530 switches.

For European organizations, especially those operating data centers, telecommunications infrastructure, or industrial control systems using Linux-based network devices with mt7530 switch chips, this vulnerability poses a risk of unauthorized data exposure and network segmentation bypass. VLAN traffic leakage can allow attackers or unauthorized users to intercept or inject traffic across logically separated networks, potentially leading to data breaches, lateral movement within networks, or disruption of network services. Organizations relying on Linux bridges for multi-tenant environments, cloud infrastructure, or critical communication networks may face confidentiality and integrity risks. The impact is heightened in regulated sectors such as finance, healthcare, and critical infrastructure, where strict network isolation is mandated. Although exploitation requires administrative privileges to configure bridges and VLAN filtering, insider threats or compromised administrative accounts could leverage this vulnerability to escalate access or exfiltrate sensitive information. The absence of known exploits reduces immediate urgency, but the vulnerability's nature warrants prompt attention to prevent future exploitation.

1. Apply the official Linux kernel patches that address CVE-2021-47160 as soon as they become available from trusted sources or Linux distributions. 2. Audit and monitor configurations of Linux bridges and VLAN filtering, especially on systems using mt7530 switches, to detect unexpected changes or traffic patterns indicative of VLAN leakage. 3. Restrict administrative access to network configuration interfaces to trusted personnel and enforce strong authentication and authorization controls to prevent unauthorized bridge or VLAN modifications. 4. Implement network segmentation monitoring tools that can detect cross-VLAN traffic anomalies, providing early warning of potential traffic leaks. 5. For environments where patching is delayed, consider disabling VLAN filtering on affected bridges or isolating vulnerable devices until remediation is applied. 6. Regularly review and update network device firmware and Linux kernel versions to incorporate security fixes and improvements. 7. Incorporate this vulnerability into vulnerability management and incident response plans to ensure rapid detection and mitigation if exploitation attempts occur.