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NVD / CVE Program· CNA Linux

CVE-2021-47386: hwmon: (w83791d) Fix NULL pointer dereference by removing unnecessary structure field

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.25% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 16887ae4e3defd2c4e7913b6c539f33eaf4eac5c, 44d3c480e4e2a75bf6296a18b4356157991ccd80, 516d9055039017a20a698103be2b556b4c976bb8.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 16887ae4e3defd2c4e7913b6c539f33eaf4eac5c, 44d3c480e4e2a75bf6296a18b4356157991ccd80, 516d9055039017a20a698103be2b556b4c976bb8 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: hwmon: (w83791d) Fix NULL pointer dereference by removing unnecessary structure field If driver read val value sufficient for (val & 0x08) && (!(val & 0x80)) && ((val & 0x7) == ((val >> 4) & 0x7)) from device then Null pointer dereference occurs. (It is possible if tmp = 0b0xyz1xyz, where same literals mean same numbers) Also lm75[] does not serve a purpose anymore after switching to devm_i2c_new_dummy_device() in w83791d_detect_subclients(). The patch fixes possible NULL pointer dereference by removing lm75[]. Found by Linux Driver Verification project (linuxtesting.org). [groeck: Dropped unnecessary continuation lines, fixed multi-line alignment]

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
May 21, 2024
Updated
Jun 17, 2026
EPSS
0.2% · 17th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernelbefore 5.4.151
  • linux linux kernel5.5 and later · before 5.10.71
  • linux linux kernel5.11 and later · before 5.14.10
  • linux linux kernel5.15

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.4affected
    • 358d2071100d84cfe6ef4a9d70ac0d998a1d501e and later · before 44d3c480e4e2a75bf6296a18b4356157991ccd80affected · git
    • 358d2071100d84cfe6ef4a9d70ac0d998a1d501e and later · before 516d9055039017a20a698103be2b556b4c976bb8affected · git
    • 358d2071100d84cfe6ef4a9d70ac0d998a1d501e and later · before 16887ae4e3defd2c4e7913b6c539f33eaf4eac5caffected · git
    • 358d2071100d84cfe6ef4a9d70ac0d998a1d501e and later · before 943c15ac1b84d378da26bba41c83c67e16499ac4affected · git
    • before 5.4not affected · semver
    • 5.4.151 and later · up to and including 5.4.*not affected · semver
    • 5.10.71 and later · up to and including 5.10.*not affected · semver
    • 5.14.10 and later · up to and including 5.14.*not affected · semver
    • 5.15 and laternot affected · original_commit_for_fix

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8bpftoolbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernelbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-abi-stablelistsbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-corebefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-cross-headersbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-debugbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-debug-corebefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-debug-develbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-debug-modulesbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-debug-modules-extrabefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-develbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-docbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-headersbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-modulesbefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-modules-extrabefore 4.18.0-553.22.1.el8_104.18.0-553.22.1.el8_10
AlmaLinux:8kernel-rtbefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10
AlmaLinux:8kernel-rt-corebefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10
AlmaLinux:8kernel-rt-debugbefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10
AlmaLinux:8kernel-rt-debug-corebefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10
AlmaLinux:8kernel-rt-debug-develbefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10
AlmaLinux:8kernel-rt-debug-kvmbefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10
AlmaLinux:8kernel-rt-debug-modulesbefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10
AlmaLinux:8kernel-rt-debug-modules-extrabefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10
AlmaLinux:8kernel-rt-develbefore 4.18.0-553.22.1.rt7.363.el8_104.18.0-553.22.1.rt7.363.el8_10

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2021-47384May 21, 2024 · hwmon: (w83793) Fix NULL pointer dereference by removing unnecessary structure field
    21Monitor
  • ← EarlierCVE-2021-47385May 21, 2024 · hwmon: (w83792d) Fix NULL pointer dereference by removing unnecessary structure field
    22Monitor
  • Later →CVE-2021-47387May 21, 2024 · cpufreq: schedutil: Use kobject release() method to free sugov_tunables
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux16887ae4e3defd2c4e7913b6c539f33eaf4eac5cVendor (CNA)
Linux Linux44d3c480e4e2a75bf6296a18b4356157991ccd80Vendor (CNA)
Linux Linux516d9055039017a20a698103be2b556b4c976bb8Vendor (CNA)
Linux Linux943c15ac1b84d378da26bba41c83c67e16499ac4Vendor (CNA)
almalinux:bpftool4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-abi-stablelists4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-core4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-cross-headers4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-core4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-devel4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules-extra4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-devel4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-doc4.18.0-553.22.1.el8_10 · AlmaLinux:8Package registry (OSV)
debian:linux5.14.12-1 · Debian:12Package registry (OSV)
red hat:bpftool0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:bpftool-debuginfo0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-abi-stablelists0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-core0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-core0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-debuginfo0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-devel0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-modules0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-modules-extra0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debuginfo0:4.18.0-553.22.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
rocky linux:kernel0:4.18.0-553.22.1.el8_10 · Rocky Linux:8Package registry (OSV)

+1

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records