CVE-2021-46940

Energy-statistics interruption via signed offset overflow

Published Feb 27, 2024 · Updated May 11, 2026

Integer overflow in Linux kernel turbostat allows local users to interrupt background energy-statistics updates during long runs. The idx_to_offset(), offset_to_idx(), and update_msr_sum() paths use signed 32-bit int offsets for unsigned MSR identifiers, so MSR_PKG_ENERGY_STAT becomes negative and trips the offset rejection check. The flaw requires local turbostat execution with long-duration timer sampling and stops statistics refreshes rather than crashing or modifying the kernel.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in Linux kernel turbostat allows local users to interrupt background energy-statistics updates during long runs. The idx_to_offset(), offset_to_idx(), and update_msr_sum() paths use signed 32-bit int offsets for unsigned MSR identifiers, so MSR_PKG_ENERGY_STAT becomes negative and trips the offset rejection check. The flaw requires local turbostat execution with long-duration timer sampling and stops statistics refreshes rather than crashing or modifying the kernel.

The record

CVE
CVE-2021-46940
Published
Feb 27, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-190
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 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=5.10
  2. Affected versionversion=9972d5d84d76982606806b2ce887f70c2f8ba60a <13a779de4175df602366d129e41782ad7168cef0
  3. Affected versionversion=9972d5d84d76982606806b2ce887f70c2f8ba60a <337b1546cde87fb8588ddaedf0201b769baa572a
  4. Affected versionversion=9972d5d84d76982606806b2ce887f70c2f8ba60a <dbdf22fc825fdb1d97f23230064e0f9819471628
  5. Affected versionversion=9972d5d84d76982606806b2ce887f70c2f8ba60a <ea6803ff2cd1a2d7d880256bf562172b708a76ff

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.10; version=9972d5d84d76982606806b2ce887f70c2f8ba60a <13a779de4175df602366d129e41782ad7168cef0; version=9972d5d84d76982606806b2ce887f70c2f8ba60a <337b1546cde87fb8588ddaedf0201b769baa572a; version=9972d5d84d76982606806b2ce887f70c2f8ba60a <dbdf22fc825fdb1d97f23230064e0f9819471628; version=9972d5d84d76982606806b2ce887f70c2f8ba60a <ea6803ff2cd1a2d7d880256bf562172b708a76ff

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 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

CWE-190Integer Overflow or Wraparound

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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