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CVE Record

CVE-2021-47325: iommu/arm-smmu: Fix arm_smmu_device refcount leak in address translation

In the Linux kernel, the following vulnerability has been resolved: iommu/arm-smmu: Fix arm_smmu_device refcount leak in address translation The reference counting issue happens in several exception handling paths of arm_smmu_iova_to_phys_hard(). When those error scenarios occur, the function forgets to decrease the refcount of "smmu" increased by arm_smmu_rpm_get(), causing a refcount leak. Fix this issue by jumping to "out" label when those error scenarios occur.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47325 is a Linux kernel bug in ARM SMMU address translation error handling. Under certain error paths, the kernel failed to release a device reference, causing a reference-count leak. The public record does not provide CVSS severity, exploitation evidence, or business-impact examples.

Executive priority

Treat this as a targeted kernel maintenance item until more evidence appears. Prioritize patching where ARM SMMU is used in production or infrastructure platforms, but do not escalate as an emergency solely from the supplied data.

Technical view

The flaw is in arm_smmu_iova_to_phys_hard(). After arm_smmu_rpm_get() increments the smmu reference count, several exception paths returned without decrementing it. The upstream fix routes those paths through the common out label so cleanup occurs consistently.

Likely exposure

Exposure appears limited to Linux systems using the ARM SMMU IOMMU driver and affected kernel versions. Organizations should map ARM-based servers, appliances, embedded platforms, or virtualization hosts to vendor kernel advisories. The source data does not identify affected distributions or non-Linux products.

Exploitation context

The CVE source bundle marks KEV as false and provides no cited evidence of active exploitation. The issue is described as a refcount leak in kernel error handling, not as a confirmed remote compromise path. Exploitability and practical impact are not established in the supplied sources.

Researcher notes

The record lacks CVSS, CWE, distribution-level fixed versions, and exploitation detail. Research should focus on affected ARM SMMU code reachability, whether unprivileged workloads can trigger the failing paths, and whether the leak creates denial-of-service risk over time.

Mitigation direction

  • Update affected Linux kernels using vendor or upstream stable guidance.
  • Prioritize ARM systems using ARM SMMU or IOMMU functionality.
  • Check distribution advisories for fixed package versions.
  • Avoid direct wrangler-style assumptions; use vendor kernel lifecycle guidance.
  • Document any deferred remediation with compensating monitoring rationale.

Validation and detection

  • Inventory Linux kernel versions across ARM-based assets.
  • Confirm whether ARM SMMU support is present and enabled.
  • Map installed kernels to vendor fixed releases or referenced stable commits.
  • Review change management records for kernel updates after publication.
  • Monitor vendor advisories for added severity or exploitability details.
Prepared
Confidence
medium
Sources
7

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-2021-47325 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
6Source 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
LinuxLinuxd4a44f0750bb9bf7c44c22444a482756b2344a79, d4a44f0750bb9bf7c44c22444a482756b2344a79, d4a44f0750bb9bf7c44c22444a482756b2344a79, d4a44f0750bb9bf7c44c22444a482756b2344a79, d4a44f0750bb9bf7c44c22444a482756b2344a79unaffected
LinuxLinux5.0, 0, 5.4.134, 5.10.52, 5.12.19, 5.13.4, 5.14affected
Weakness

CWE details

No CWE listed

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