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CVE Record

CVE-2021-47235: net: ethernet: fix potential use-after-free in ec_bhf_remove

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: fix potential use-after-free in ec_bhf_remove static void ec_bhf_remove(struct pci_dev *dev) { ... struct ec_bhf_priv *priv = netdev_priv(net_dev); unregister_netdev(net_dev); free_netdev(net_dev); pci_iounmap(dev, priv->dma_io); pci_iounmap(dev, priv->io); ... } priv is netdev private data, but it is used after free_netdev(). It can cause use-after-free when accessing priv pointer. So, fix it by moving free_netdev() after pci_iounmap() calls.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47235 is a Linux kernel memory-safety bug in an Ethernet driver removal path. The code could use driver-private memory after it was freed. The public bundle does not provide a CVSS score, business impact rating, or evidence of active exploitation.

Executive priority

Treat this as a kernel maintenance item unless local inventory shows use of the affected driver path on important systems. No active exploitation or severity score is provided, so urgency should be driven by exposure and normal patch cadence.

Technical view

The issue is a potential use-after-free in ec_bhf_remove(). The function frees the netdev, then accesses priv, which is netdev private data, while unmapping PCI I/O regions. The kernel fix reorders cleanup so pci_iounmap() calls happen before free_netdev().

Likely exposure

Exposure appears limited to Linux systems running affected kernel versions and the relevant Ethernet driver path. The bundle lists Linux kernel versions including 3.15 through 5.13-era stable releases, but does not identify distributions, default configurations, or reachable attack paths.

Exploitation context

The source bundle marks KEV as false and provides no cited evidence of public exploitation. The bug is in cleanup/removal logic, so practical risk likely depends on driver presence, hardware, privileges, and whether the removal path can be triggered.

Researcher notes

Evidence supports a use-after-free caused by cleanup ordering in ec_bhf_remove(). The bundle does not provide CVSS, CWE, exploitability analysis, distribution mappings, or runtime prerequisites. Further assessment should focus on driver reachability and backport status in deployed kernels.

Mitigation direction

  • Apply vendor-supported Linux kernel updates containing the referenced stable fixes.
  • Prioritize systems using the relevant Ethernet driver or matching hardware path.
  • Check distribution advisories for CVE-2021-47235 before choosing a package version.
  • Avoid relying on upstream commit hashes alone for distribution kernels.
  • Schedule reboots or live-patching according to normal kernel maintenance policy.

Validation and detection

  • Inventory Linux kernel versions against the affected version list in the CVE bundle.
  • Confirm whether the relevant Ethernet driver is built, loaded, or used.
  • Verify kernel changelogs mention CVE-2021-47235 or the referenced stable commits.
  • Review asset records for systems with matching PCI Ethernet hardware.
  • After patching, confirm the running kernel is the updated build.
Prepared
Confidence
medium
Sources
10

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-2021-47235 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
9Source 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
LinuxLinux6af55ff52b02d492d45db88df3e461fa51a6f753, 6af55ff52b02d492d45db88df3e461fa51a6f753, 6af55ff52b02d492d45db88df3e461fa51a6f753, 6af55ff52b02d492d45db88df3e461fa51a6f753, 6af55ff52b02d492d45db88df3e461fa51a6f753, 6af55ff52b02d492d45db88df3e461fa51a6f753, 6af55ff52b02d492d45db88df3e461fa51a6f753, 6af55ff52b02d492d45db88df3e461fa51a6f753unaffected
LinuxLinux3.15, 0, 4.4.274, 4.9.274, 4.14.238, 4.19.196, 5.4.128, 5.10.46, 5.12.13, 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.