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CVE Record

CVE-2021-47021: mt76: mt7915: fix memleak when mt7915_unregister_device()

In the Linux kernel, the following vulnerability has been resolved: mt76: mt7915: fix memleak when mt7915_unregister_device() mt7915_tx_token_put() should get call before mt76_free_pending_txwi().

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel memory leak in the mt76 mt7915 Wi-Fi driver cleanup path. It appears tied to unregistering a device, not direct remote compromise. Business urgency depends on whether affected kernels run this driver in production or embedded environments.

Executive priority

Treat this as a targeted kernel maintenance item unless affected mt7915-based devices are important to operations. Prioritize normal kernel patch cycles and embedded fleet review, with higher urgency if vendor guidance reports operational instability.

Technical view

The fix changes mt7915_unregister_device() cleanup ordering so mt7915_tx_token_put() runs before mt76_free_pending_txwi(). Without that order, resources associated with transmit tokens can leak during device unregister. The source bundle does not provide CVSS, CWE, crash impact, or broader attack prerequisites.

Likely exposure

Exposure is most likely on Linux systems using affected kernel builds with the mt76 mt7915 driver present and relevant hardware or module usage. The provided data is incomplete on exact downstream distro package versions and affected device models.

Exploitation context

No active exploitation is cited, and the CVE is not listed as KEV in the source bundle. The available description supports a resource-leak cleanup bug, but does not establish remote exploitability, privilege escalation, or denial-of-service conditions.

Researcher notes

The public bundle only identifies a resolved Linux kernel memory leak and three kernel stable commits. It lacks CVSS, CWE, exploitability notes, and distro mappings, so validation should focus on driver presence and whether the cleanup-order fix is backported.

Mitigation direction

  • Check Linux vendor or distribution advisories for fixed kernel packages.
  • Update kernels to versions containing the referenced stable mt7915 cleanup fix.
  • Prioritize systems that load or ship the mt76 mt7915 driver.
  • If patching is delayed, reduce use of affected hardware or driver where operationally feasible.

Validation and detection

  • Inventory Linux kernel versions across servers, appliances, and embedded builds.
  • Check whether the mt76 mt7915 driver is built, installed, or loaded.
  • Confirm kernel source or package includes one of the referenced stable fixes.
  • Review vendor backport notes because fixed downstream package versions may differ.
Prepared
Confidence
medium
Sources
5

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-2021-47021 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
4Source 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
LinuxLinux4e9e896f81932e337a93ad61cd3d9647571c4637, f285dfb98562e8380101095d168910df1d07d8be, f285dfb98562e8380101095d168910df1d07d8beunaffected
LinuxLinux5.12, 0, 5.11.21, 5.12.4, 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.