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CVE Record

CVE-2021-47064: mt76: fix potential DMA mapping leak

In the Linux kernel, the following vulnerability has been resolved: mt76: fix potential DMA mapping leak With buf uninitialized in mt76_dma_tx_queue_skb_raw, its field skip_unmap could potentially inherit a non-zero value from stack garbage. If this happens, it will cause DMA mappings for MCU command frames to not be unmapped after completion

MediumCVSS 5.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-47064 is a Linux kernel mt76 wireless driver flaw that can leak DMA mappings. The documented impact is reduced availability, not data theft or tampering. Business urgency is highest for systems running affected Linux kernels with MediaTek mt76 wireless hardware or embedded Linux images using that driver.

Executive priority

Treat as a moderate infrastructure hygiene issue. Patch through normal kernel maintenance, prioritizing wireless-enabled Linux systems and embedded devices. Escalate only if critical services depend on affected mt76 hardware or vendor patch status is unknown.

Technical view

In mt76_dma_tx_queue_skb_raw, an uninitialized buffer field, skip_unmap, could inherit a non-zero stack value. When that happens, DMA mappings for MCU command frames may not be unmapped after completion. The CVSS 3.1 score is 5.3 with availability impact only.

Likely exposure

Exposure appears limited to Linux systems using affected kernel versions and the mt76 driver path. The source lists Linux 5.10 through 5.13-related affected entries and stable kernel fixes, but does not identify specific distributions, appliances, or hardware models.

Exploitation context

The bundle does not report active exploitation, and KEV status is false. The CVSS vector is network reachable with low complexity and no privileges, but the sources do not provide practical exploitability details or public exploitation evidence.

Researcher notes

The record supports a DMA mapping leak in the mt76 transmit path caused by uninitialized skip_unmap state. Evidence is limited to Linux kernel resolution text, CVSS metadata, and stable commit references. No confidentiality or integrity impact is stated, and no exploit mechanics are provided.

Mitigation direction

  • Apply vendor kernel updates that include the referenced Linux stable fixes.
  • Prioritize systems using mt76 wireless hardware or embedded Linux wireless stacks.
  • For appliances, request vendor confirmation that the fix is included.
  • If no update is available, follow vendor guidance for risk reduction.
  • Track distribution advisories for supported kernel backports.

Validation and detection

  • Inventory Linux kernel versions across affected assets.
  • Confirm whether mt76 wireless driver support is present or loaded.
  • Check vendor kernel changelogs for the referenced stable commits.
  • Validate distribution advisories against installed kernel package versions.
  • Monitor systems for availability symptoms if patching is delayed.
Prepared
Confidence
high
Sources
6

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.

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CVE-2021-47064 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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.

1CVSS vectors
3Timeline events
2ADP providers
5Source links

SSVC decision data

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

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L3.91.4CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

5.3Medium
CVSS 3.1 vector shape for CVE-2021-47064Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux27d5c528a7ca08dcd44877fdd9fc08b76630bf77, 27d5c528a7ca08dcd44877fdd9fc08b76630bf77, 27d5c528a7ca08dcd44877fdd9fc08b76630bf77, 27d5c528a7ca08dcd44877fdd9fc08b76630bf77unaffected
LinuxLinux5.10, 0, 5.10.37, 5.11.21, 5.12.4, 5.13affected
Weakness

CWE details

No CWE listed

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