CVE-2021-47025

Kernel warning via unbalanced IOMMU clock disable

Published Feb 28, 2024 · Updated May 11, 2026

A clock-state bug in Linux 5.12 allows local users to trigger a kernel warning during MediaTek IOMMU runtime power transitions. The mtk_iommu_runtime_resume function skips clock enablement when m4u_dom is null, after which the suspend callback disables an already-disabled clock. Reachability requires a MediaTek IOMMU device and runtime suspend activity; the published trace shows a warning, not a demonstrated crash or code execution.

CVSS severity7.8
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A clock-state bug in Linux 5.12 allows local users to trigger a kernel warning during MediaTek IOMMU runtime power transitions. The mtk_iommu_runtime_resume function skips clock enablement when m4u_dom is null, after which the suspend callback disables an already-disabled clock. Reachability requires a MediaTek IOMMU device and runtime suspend activity; the published trace shows a warning, not a demonstrated crash or code execution.

The record

CVE
CVE-2021-47025
Published
Feb 28, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.12
  2. Affected versionversion=c0b57581b73be7b43f39e0dff201c93413f6a668 <5cad9e2caa9613fdcd246bd4ebf0ffbec1cba2ca
  3. Affected versionversion=c0b57581b73be7b43f39e0dff201c93413f6a668 <b34ea31fe013569d42b7e8681ef3f717f77c5b72

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=c0b57581b73be7b43f39e0dff201c93413f6a668 <5cad9e2caa9613fdcd246bd4ebf0ffbec1cba2ca; version=c0b57581b73be7b43f39e0dff201c93413f6a668 <b34ea31fe013569d42b7e8681ef3f717f77c5b72

Published CVSS scores

7.8Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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