CVE-2021-47393

Kernel memory disclosure via fan-state table overread

Published May 21, 2024 · Updated May 11, 2026

An out-of-bounds read in the Linux kernel mlxreg-fan driver allows local users to read kernel memory through a sysfs write. mlxreg_fan_set_cur_state incorrectly returns success for an enforced fan state above the normal maximum, causing thermal_cooling_device_stats_update to index beyond its statistics table. The affected path requires supported Mellanox fan hardware, write access to the cooling-state sysfs file, and CONFIG_THERMAL_STATISTICS; the resulting read can disclose memory or crash the kernel.

CVSS severity7.1
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An out-of-bounds read in the Linux kernel mlxreg-fan driver allows local users to read kernel memory through a sysfs write. mlxreg_fan_set_cur_state incorrectly returns success for an enforced fan state above the normal maximum, causing thermal_cooling_device_stats_update to index beyond its statistics table. The affected path requires supported Mellanox fan hardware, write access to the cooling-state sysfs file, and CONFIG_THERMAL_STATISTICS; the resulting read can disclose memory or crash the kernel.

The record

CVE
CVE-2021-47393
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-125
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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=4.19
  2. Affected versionversion=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <5c6e0bce647d9cb32a17d58ffa669b3421fcc6ca
  3. Affected versionversion=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <76bbb482d33bfcd7e9070ecf594c9ec73e01c930
  4. Affected versionversion=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <a6c42ae1530f94724d3c42cf91fe3d3c5e394f8a
  5. Affected versionversion=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <aa85fb7bde558bb2e364e85976b14b259c8b6fe8
  6. Affected versionversion=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <e6fab7af6ba1bc77c78713a83876f60ca7a4a064

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.19; version=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <5c6e0bce647d9cb32a17d58ffa669b3421fcc6ca; version=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <76bbb482d33bfcd7e9070ecf594c9ec73e01c930; version=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <a6c42ae1530f94724d3c42cf91fe3d3c5e394f8a; version=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <aa85fb7bde558bb2e364e85976b14b259c8b6fe8; version=65afb4c8e7e4e7e74b28efa1df62da503ca3e7a6 <e6fab7af6ba1bc77c78713a83876f60ca7a4a064

Published CVSS scores

7.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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-125Out-of-bounds Read

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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