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CVE Record

CVE-2021-47416: phy: mdio: fix memory leak

In the Linux kernel, the following vulnerability has been resolved: phy: mdio: fix memory leak Syzbot reported memory leak in MDIO bus interface, the problem was in wrong state logic. MDIOBUS_ALLOCATED indicates 2 states: 1. Bus is only allocated 2. Bus allocated and __mdiobus_register() fails, but device_register() was called In case of device_register() has been called we should call put_device() to correctly free the memory allocated for this device, but mdiobus_free() calls just kfree(dev) in case of MDIOBUS_ALLOCATED state To avoid this behaviour we need to set bus->state to MDIOBUS_UNREGISTERED _before_ calling device_register(), because put_device() should be called even in case of device_register() failure.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel memory leak in the MDIO bus interface, used around network PHY device handling. The public record describes incorrect cleanup logic after device registration failure. No source in the bundle reports active exploitation or a CVSS score.

Executive priority

Treat as routine kernel hygiene unless affected custom or embedded network devices are business-critical. The absence of CVSS and exploitation evidence lowers urgency, but kernel backport tracking is still required.

Technical view

The flaw is in MDIO bus state handling. When __mdiobus_register() fails after device_register() was called, mdiobus_free() could kfree() the structure instead of using put_device(), leaving device-managed memory unreleased. Stable kernel commits adjust state handling before device_register().

Likely exposure

Exposure is most plausible on Linux systems using affected kernel versions and MDIO/PHY networking paths, especially embedded, appliance, and network-device builds. The bundle does not identify a remote attack surface or affected distributions.

Exploitation context

The issue was reported by syzbot as a memory leak. KEV is false, and the provided sources do not claim exploitation in the wild, public exploit availability, privilege impact, or reliable denial-of-service conditions.

Researcher notes

Evidence is limited to the CVE description and Linux stable commit references. The source bundle supports a memory-leak classification but does not provide exploitability details, affected distro package names, or operational workarounds.

Mitigation direction

  • Update to a Linux kernel or vendor package containing the stable MDIO fix.
  • Prioritize embedded and network-facing systems with custom kernels or PHY drivers.
  • If using a vendor kernel, verify whether the fix was backported.
  • If no patch is available, monitor vendor guidance for supported mitigations.

Validation and detection

  • Inventory Linux kernel versions across servers, appliances, and embedded images.
  • Check vendor changelogs or kernel source for the referenced MDIO fix commits.
  • Identify systems using MDIO/PHY network drivers or custom kernel builds.
  • Review memory-leak telemetry for affected test or staging kernels.
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-2021-47416 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
LinuxLinux46abc02175b3c246dd5141d878f565a8725060c9, 46abc02175b3c246dd5141d878f565a8725060c9, 46abc02175b3c246dd5141d878f565a8725060c9, 46abc02175b3c246dd5141d878f565a8725060c9, 46abc02175b3c246dd5141d878f565a8725060c9, 46abc02175b3c246dd5141d878f565a8725060c9, 46abc02175b3c246dd5141d878f565a8725060c9, 46abc02175b3c246dd5141d878f565a8725060c9unaffected
LinuxLinux2.6.28, 0, 4.4.289, 4.9.287, 4.14.251, 4.19.211, 5.4.153, 5.10.73, 5.14.12, 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.