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CVE Record

CVE-2021-47372: net: macb: fix use after free on rmmod

In the Linux kernel, the following vulnerability has been resolved: net: macb: fix use after free on rmmod plat_dev->dev->platform_data is released by platform_device_unregister(), use of pclk and hclk is a use-after-free. Since device unregister won't need a clk device we adjust the function call sequence to fix this issue. [ 31.261225] BUG: KASAN: use-after-free in macb_remove+0x77/0xc6 [macb_pci] [ 31.275563] Freed by task 306: [ 30.276782] platform_device_release+0x25/0x80

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47372 is a Linux kernel use-after-free in the MACB network driver during module removal. It appears tied to driver unload or device teardown behavior, not ordinary remote network traffic. The sources provide no CVSS score and no evidence of active exploitation.

Executive priority

Treat as targeted maintenance unless your fleet uses Linux systems with MACB Ethernet hardware. The business urgency rises for embedded, operational, or appliance environments where kernel crashes affect availability and patch windows are infrequent.

Technical view

The kernel fix changes the macb remove path because platform_device_unregister() releases platform_data before later pclk and hclk use, causing use-after-free. KASAN observed the fault in macb_remove within macb_pci. Stable kernel commits are referenced as the resolution.

Likely exposure

Exposure is likely limited to Linux systems using the MACB/macb_pci Ethernet driver and affected kernel versions or unpatched backports. Systems not using that driver are less likely exposed. Version data in the bundle is incomplete and should be verified against distro kernel packages.

Exploitation context

The source describes a use-after-free on rmmod and does not provide a public exploit, CVSS vector, or remote attack evidence. CISA KEV status is false in the bundle, so active exploitation should not be claimed from these sources.

Researcher notes

The public record identifies the flawed lifetime ordering and stable commits but omits CVSS, CWE, and exploitability detail. Focus analysis on affected driver presence, module unload paths, and whether vendor kernels have backported the fix despite different version strings.

Mitigation direction

  • Update to a vendor kernel release that includes the referenced stable fixes.
  • Check distribution advisories for CVE-2021-47372 backport status.
  • Avoid unnecessary MACB driver unloads on affected systems until patched.
  • Prioritize embedded or appliance Linux systems using MACB Ethernet hardware.

Validation and detection

  • Inventory Linux kernel versions and MACB/macb_pci driver usage.
  • Confirm the running kernel includes a referenced stable fix or vendor backport.
  • Review kernel logs for KASAN, oops, or macb_remove use-after-free messages.
  • Verify remediation after reboot by checking the active kernel package.
Prepared
Confidence
medium
Sources
8

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-2021-47372 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
7Source 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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux83a77e9ec4150ee4acc635638f7dedd9da523a26, 83a77e9ec4150ee4acc635638f7dedd9da523a26, 83a77e9ec4150ee4acc635638f7dedd9da523a26, 83a77e9ec4150ee4acc635638f7dedd9da523a26, 83a77e9ec4150ee4acc635638f7dedd9da523a26, 83a77e9ec4150ee4acc635638f7dedd9da523a26unaffected
LinuxLinux4.10, 0, 4.14.249, 4.19.209, 5.4.150, 5.10.70, 5.14.9, 5.15affected
Weakness

CWE details

No CWE listed

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