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CVE Record

CVE-2021-47160: net: dsa: mt7530: fix VLAN traffic leaks

In the Linux kernel, the following vulnerability has been resolved: net: dsa: mt7530: fix VLAN traffic leaks PCR_MATRIX field was set to all 1's when VLAN filtering is enabled, but was not reset when it is disabled, which may cause traffic leaks: ip link add br0 type bridge vlan_filtering 1 ip link add br1 type bridge vlan_filtering 1 ip link set swp0 master br0 ip link set swp1 master br1 ip link set br0 type bridge vlan_filtering 0 ip link set br1 type bridge vlan_filtering 0 # traffic in br0 and br1 will start leaking to each other As port_bridge_{add,del} have set up PCR_MATRIX properly, remove the PCR_MATRIX write from mt7530_port_set_vlan_aware.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can let traffic cross between bridge or VLAN-separated networks on systems using the MT7530 switch driver. That weakens network isolation and may expose traffic to the wrong segment. The sources do not provide a CVSS score or evidence of active exploitation.

Executive priority

Prioritize remediation for routers, switches, and embedded network appliances that enforce customer, tenant, or security-zone separation. Business urgency is lower for systems without MT7530 hardware, but affected boundary devices should be patched because isolation failure can undermine network trust assumptions.

Technical view

The mt7530 DSA driver set PCR_MATRIX when VLAN filtering was enabled but did not reset it when VLAN filtering was disabled. The stale port matrix could allow traffic leakage between bridge domains. Kernel stable commits remove the problematic PCR_MATRIX write from mt7530_port_set_vlan_aware.

Likely exposure

Exposure appears limited to Linux systems using the MediaTek MT7530 DSA switch driver, especially embedded routers, switches, or appliances that change bridge VLAN filtering state. Generic Linux servers without this driver or topology are less likely to be affected.

Exploitation context

No KEV listing or cited source indicates active exploitation. The public description shows the condition that causes leakage, but not a weaponized exploit. Risk is mainly segmentation failure and unintended traffic visibility inside affected local network environments.

Researcher notes

The evidence supports a driver logic flaw causing traffic leaks after VLAN filtering state changes. The bundle does not include CVSS, CWE mapping, exploit maturity, or product-level advisories beyond Linux kernel references. Treat downstream vendor firmware status as a separate verification task.

Mitigation direction

  • Update affected Linux kernels to versions containing the referenced stable fixes.
  • Check device vendor firmware advisories for MT7530-based products.
  • Avoid unnecessary runtime toggling of bridge VLAN filtering on affected systems.
  • Review network segmentation assumptions for MT7530-based infrastructure.

Validation and detection

  • Inventory Linux appliances using the mt7530 DSA switch driver.
  • Confirm deployed kernel or firmware includes the stable fix commits.
  • Review bridge configurations where VLAN filtering is enabled or disabled.
  • Validate segment isolation in an approved lab or maintenance window.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-47160 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux83163f7dca5684816d01c8ccf4857aa74801e7b7, 83163f7dca5684816d01c8ccf4857aa74801e7b7, 83163f7dca5684816d01c8ccf4857aa74801e7b7, 83163f7dca5684816d01c8ccf4857aa74801e7b7, 83163f7dca5684816d01c8ccf4857aa74801e7b7unaffected
LinuxLinux4.16, 0, 4.19.193, 5.4.124, 5.10.42, 5.12.9, 5.13affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.