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CVE Record

CVE-2021-47500: iio: mma8452: Fix trigger reference couting

In the Linux kernel, the following vulnerability has been resolved: iio: mma8452: Fix trigger reference couting The mma8452 driver directly assigns a trigger to the struct iio_dev. The IIO core when done using this trigger will call `iio_trigger_put()` to drop the reference count by 1. Without the matching `iio_trigger_get()` in the driver the reference count can reach 0 too early, the trigger gets freed while still in use and a use-after-free occurs. Fix this by getting a reference to the trigger before assigning it to the IIO device.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47500 is a Linux kernel bug in the mma8452 IIO driver. A missing reference count increment can let a trigger object be freed while still in use, causing a use-after-free. Business urgency depends on whether affected Linux kernels actually use this driver.

Executive priority

Treat this as targeted kernel maintenance, not an internet-scale emergency based on current evidence. Prioritize embedded, appliance, or hardware-adjacent Linux assets that may use this driver, and fold remediation into normal kernel patch cycles unless vendor guidance raises urgency.

Technical view

The mma8452 driver assigns a trigger to struct iio_dev without first taking a matching iio_trigger_get() reference. When the IIO core later calls iio_trigger_put(), the reference count may drop to zero prematurely, freeing the trigger while it remains reachable.

Likely exposure

Exposure appears limited to Linux systems running affected kernel versions with the mma8452 IIO driver present and exercised. The CVE record lists affected Linux kernel version branches, but no product-specific downstream distribution status is provided.

Exploitation context

The provided sources do not report active exploitation, public exploit code, or KEV listing. The impact is described as kernel use-after-free, but practical exploitability, required privileges, and reachable attack paths are not established in the bundle.

Researcher notes

The core issue is lifetime management: missing iio_trigger_get() before assigning indio_dev->trig permits premature iio_trigger_put() cleanup. The bundle does not provide CVSS, CWE, exploit prerequisites, or downstream distro mapping, so exposure validation should be asset-specific.

Mitigation direction

  • Update to a kernel containing the referenced stable fixes.
  • Check Linux vendor advisories for distribution-specific fixed kernel packages.
  • Prioritize systems that enable or load the mma8452 IIO driver.
  • Disable unused affected hardware support where vendor guidance allows.

Validation and detection

  • Inventory running kernel versions and loaded mma8452-related modules.
  • Compare kernel source or package changelogs against the referenced stable commits.
  • Confirm whether affected systems use IIO triggers with this driver.
  • Track vendor advisories for backported fixes and package status.
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

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CVE-2021-47500 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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxae6d9ce05691bf79694074db7c7da980080548af, ae6d9ce05691bf79694074db7c7da980080548af, ae6d9ce05691bf79694074db7c7da980080548af, ae6d9ce05691bf79694074db7c7da980080548af, ae6d9ce05691bf79694074db7c7da980080548af, ae6d9ce05691bf79694074db7c7da980080548af, ae6d9ce05691bf79694074db7c7da980080548af, ae6d9ce05691bf79694074db7c7da980080548afunaffected
LinuxLinux4.2, 0, 4.4.295, 4.9.293, 4.14.258, 4.19.221, 5.4.165, 5.10.85, 5.15.8, 5.16affected
Weakness

CWE details

No CWE listed

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