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CVE Record

CVE-2021-46940: tools/power turbostat: Fix offset overflow issue in index converting

In the Linux kernel, the following vulnerability has been resolved: tools/power turbostat: Fix offset overflow issue in index converting The idx_to_offset() function returns type int (32-bit signed), but MSR_PKG_ENERGY_STAT is u32 and would be interpreted as a negative number. The end result is that it hits the if (offset < 0) check in update_msr_sum() which prevents the timer callback from updating the stat in the background when long durations are used. The similar issue exists in offset_to_idx() and update_msr_sum(). Fix this issue by converting the 'int' to 'off_t' accordingly.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This CVE concerns Linux turbostat, a power and CPU statistics tool, not a network-facing service. A signed integer overflow can cause long-running measurements to stop updating one energy statistic. Based on the supplied sources, the business impact appears to be monitoring accuracy, not system compromise.

Executive priority

Handle through normal patch management unless turbostat data drives operational or financial decisions. There is no supplied evidence of active exploitation or direct compromise risk, but unreliable telemetry can still affect planning and incident analysis.

Technical view

idx_to_offset() returned a 32-bit signed int while MSR_PKG_ENERGY_STAT is u32, causing some offsets to be interpreted as negative. update_msr_sum() then rejects the value, preventing background statistic updates during long-duration turbostat runs. Related conversions in offset_to_idx() and update_msr_sum() were changed to off_t.

Likely exposure

Exposure is most likely where affected Linux versions use turbostat for long-running CPU package energy or power telemetry. The source marks Linux 5.10, 5.10.36, 5.11.20, 5.12.3, and 5.13 as affected. It does not identify remote exposure or privilege-impacting attack paths.

Exploitation context

The bundle provides no CVSS score, CWE, exploit report, or CISA KEV listing. There is no evidence here of active exploitation. The described failure mode is incorrect or missing telemetry updates under long durations, which limits direct attacker value based on available evidence.

Researcher notes

The source evidence is narrow: it describes a type-conversion bug and stable kernel fixes. It does not establish exploitability beyond telemetry failure. Validate by code provenance and package advisory mapping, not by assuming all Linux systems are materially exposed.

Mitigation direction

  • Update to a vendor kernel or turbostat package containing the referenced stable fixes.
  • Check Linux distribution advisories for the exact fixed package version in your environment.
  • Prioritize systems relying on turbostat telemetry for capacity, billing, or operational decisions.
  • Document any monitoring blind spots caused by affected long-duration turbostat runs.

Validation and detection

  • Inventory Linux versions and turbostat package sources on monitored hosts.
  • Confirm whether the stable fix commits are present in your kernel source or package changelog.
  • Review long-duration turbostat output for missing package energy statistic updates.
  • Verify vendor advisories before treating a build as fixed.
Prepared
Confidence
medium
Sources
6

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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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
5Source 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
LinuxLinux9972d5d84d76982606806b2ce887f70c2f8ba60a, 9972d5d84d76982606806b2ce887f70c2f8ba60a, 9972d5d84d76982606806b2ce887f70c2f8ba60a, 9972d5d84d76982606806b2ce887f70c2f8ba60aunaffected
LinuxLinux5.10, 0, 5.10.36, 5.11.20, 5.12.3, 5.13affected
Weakness

CWE details

No CWE listed

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