CVE-2026-31741

Local PWM interruption via repeated counter toggles

Published May 1, 2026 · Updated May 1, 2026

Improper state management in the Linux kernel rz-mtu3 counter driver allows local users to interrupt PWM output through sysfs. The driver's enable handler changes runtime PM usage on every write without first comparing the requested value with count_is_enabled, so repeated disables underflow the count and access registers with clocks off. Write access to the counter enable attribute is required; disabling it during active PWM stops output even when the counter does not own the MTU3 channel.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper state management in the Linux kernel rz-mtu3 counter driver allows local users to interrupt PWM output through sysfs. The driver's enable handler changes runtime PM usage on every write without first comparing the requested value with count_is_enabled, so repeated disables underflow the count and access registers with clocks off. Write access to the counter enable attribute is required; disabling it during active PWM stops output even when the counter does not own the MTU3 channel.

The record

CVE
CVE-2026-31741
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 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=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <67c3f99bed6f422ba343d2b70a2eeeccdfd91bef
  2. Affected versionversion=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <885aa739a07ab45e90dfa997205acec97979ce4e
  3. Affected versionversion=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <ced8b48420eddb1251f93c22dc23fa136490b3cd
  4. Affected versionversion=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <e07237df8538b0ae98dce112e4f6db093d767f80
  5. Affected versionversion=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <f5f6f06d7e6d262026578b59ba7426eb04acce5d
  6. Affected versionversion=6.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <67c3f99bed6f422ba343d2b70a2eeeccdfd91bef; version=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <885aa739a07ab45e90dfa997205acec97979ce4e; version=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <ced8b48420eddb1251f93c22dc23fa136490b3cd; version=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <e07237df8538b0ae98dce112e4f6db093d767f80; version=0be8907359df4c62319f5cb2c6981ff0d9ebf35a <f5f6f06d7e6d262026578b59ba7426eb04acce5d; version=6.4

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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