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NVD / CVE Program· CNA Linux

CVE-2021-47476: comedi: ni_usb6501: fix NULL-deref in command paths

Noroxi assessment

Priority: Monitor (action score 18/100)

  • 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: 0.38% (FIRST EPSS).
  • Physical access to the device is required. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 4a9d43cb5d5f39fa39fc1da438517004cc95f7ea, 58478143771b20ab219937b1c30a706590a59224, 907767da8f3a925b060c740e0b5c92ea7dbec440.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 4a9d43cb5d5f39fa39fc1da438517004cc95f7ea, 58478143771b20ab219937b1c30a706590a59224, 907767da8f3a925b060c740e0b5c92ea7dbec440 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: comedi: ni_usb6501: fix NULL-deref in command paths The driver uses endpoint-sized USB transfer buffers but had no sanity checks on the sizes. This can lead to zero-size-pointer dereferences or overflowed transfer buffers in ni6501_port_command() and ni6501_counter_command() if a (malicious) device has smaller max-packet sizes than expected (or when doing descriptor fuzz testing). Add the missing sanity checks to probe().

MediumCVSS 4.6 · v3.1—No exploit Fix available
Published
May 22, 2024
Updated
Jun 17, 2026
EPSS
0.3% · 33th percentile

Report tools

JSON

Action score

18

Monitor

Low priority for now.

CVSS
18 / 40 · 4.6 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-47476

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • 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 kernel3.18 and later · before 4.4.292
  • linux linux kernel4.5 and later · before 4.9.290
  • linux linux kernel4.10 and later · before 4.14.255
  • linux linux kernel4.15 and later · before 4.19.217
  • linux linux kernel4.20 and later · before 5.4.159
  • linux linux kernel5.5 and later · before 5.10.79
  • linux linux kernel5.11 and later · before 5.14.18
  • linux linux kernel5.15 and later · before 5.15.2

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

    • 3.18affected
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before 58478143771b20ab219937b1c30a706590a59224affected · git
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before aa39738423503825625853b643b9e99d11c23816affected · git
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before df7b1238f3b599a0b9284249772cdfd1ea83a632affected · git
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before bc51111bf6e8e7b6cc94b133e4c291273a16acd1affected · git
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before b0156b7c9649d8f55a2ce3d3258509f1b2a181c3affected · git
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before ef143dc0c3defe56730ecd3a9de7b3e1d7e557c1affected · git
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before 4a9d43cb5d5f39fa39fc1da438517004cc95f7eaaffected · git
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before d6a727a681a39ae4f73081a9bedb45d14f95bdd1affected · git
    • a03bb00e50ab4c07107da58a52a0bff7943f360c and later · before 907767da8f3a925b060c740e0b5c92ea7dbec440affected · git

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 5.15.3-15.15.3-1

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-2021-47474May 22, 2024 · comedi: vmk80xx: fix bulk-buffer overflow
    31Monitor
  • ← EarlierCVE-2021-47475May 22, 2024 · comedi: vmk80xx: fix transfer-buffer overflows
    31Monitor
  • Later →CVE-2021-47477May 22, 2024 · comedi: dt9812: fix DMA buffers on stack
    31Monitor

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 Linux4a9d43cb5d5f39fa39fc1da438517004cc95f7eaVendor (CNA)
Linux Linux58478143771b20ab219937b1c30a706590a59224Vendor (CNA)
Linux Linux907767da8f3a925b060c740e0b5c92ea7dbec440Vendor (CNA)
Linux Linuxaa39738423503825625853b643b9e99d11c23816Vendor (CNA)
Linux Linuxb0156b7c9649d8f55a2ce3d3258509f1b2a181c3Vendor (CNA)
Linux Linuxbc51111bf6e8e7b6cc94b133e4c291273a16acd1Vendor (CNA)
Linux Linuxd6a727a681a39ae4f73081a9bedb45d14f95bdd1Vendor (CNA)
Linux Linuxdf7b1238f3b599a0b9284249772cdfd1ea83a632Vendor (CNA)
Linux Linuxef143dc0c3defe56730ecd3a9de7b3e1d7e557c1Vendor (CNA)
debian:linux5.15.3-1 · Debian:12Package registry (OSV)

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

  • Physical access to the device is required.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Physical
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 (8 more)

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

All records