CVE-2021-47542

Kernel crash via unchecked mailbox allocation failure

Published May 24, 2024 · Updated May 11, 2026

NULL pointer dereference in the Linux kernel qlcnic driver allows local users to crash the kernel during receive-ring setup. qlcnic_83xx_add_rings dereferences cmd.req.arg without checking whether alloc_mbx_args failed to allocate the mailbox arguments. Reachability requires the qlcnic driver and an allocation failure while additional receive rings are configured; the static-analysis report notes that this condition is hard to trigger.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux kernel qlcnic driver allows local users to crash the kernel during receive-ring setup. qlcnic_83xx_add_rings dereferences cmd.req.arg without checking whether alloc_mbx_args failed to allocate the mailbox arguments. Reachability requires the qlcnic driver and an allocation failure while additional receive rings are configured; the static-analysis report notes that this condition is hard to trigger.

The record

CVE
CVE-2021-47542
Published
May 24, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 24, 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=3.9
  2. Affected versionversion=7f9664525f9cb507de9198a395a111371413f230 <15fa12c119f869173f9b710cbe6a4a14071d2105
  3. Affected versionversion=7f9664525f9cb507de9198a395a111371413f230 <3a061d54e260b701b538873b43e399d9b8b83e03
  4. Affected versionversion=7f9664525f9cb507de9198a395a111371413f230 <550658a2d61e4eaf522c8ebc7fad76dc376bfb45
  5. Affected versionversion=7f9664525f9cb507de9198a395a111371413f230 <57af54a56024435d83e44c78449513b414eb6edf
  6. Affected versionversion=7f9664525f9cb507de9198a395a111371413f230 <b4f217d6fcc00c3fdc0921a7691f30be7490b073
  7. Affected versionversion=7f9664525f9cb507de9198a395a111371413f230 <bbeb0325a7460ebf1e03f5e0bfc5c652fba9519f
  8. Affected versionversion=7f9664525f9cb507de9198a395a111371413f230 <c5ef33c1489b2cd74368057fa00b5d2183bb5853
  9. Affected versionversion=7f9664525f9cb507de9198a395a111371413f230 <e2dabc4f7e7b60299c20a36d6a7b24ed9bf8e572

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.9; version=7f9664525f9cb507de9198a395a111371413f230 <15fa12c119f869173f9b710cbe6a4a14071d2105; version=7f9664525f9cb507de9198a395a111371413f230 <3a061d54e260b701b538873b43e399d9b8b83e03; version=7f9664525f9cb507de9198a395a111371413f230 <550658a2d61e4eaf522c8ebc7fad76dc376bfb45; version=7f9664525f9cb507de9198a395a111371413f230 <57af54a56024435d83e44c78449513b414eb6edf; version=7f9664525f9cb507de9198a395a111371413f230 <b4f217d6fcc00c3fdc0921a7691f30be7490b073; version=7f9664525f9cb507de9198a395a111371413f230 <bbeb0325a7460ebf1e03f5e0bfc5c652fba9519f; version=7f9664525f9cb507de9198a395a111371413f230 <c5ef33c1489b2cd74368057fa00b5d2183bb5853; version=7f9664525f9cb507de9198a395a111371413f230 <e2dabc4f7e7b60299c20a36d6a7b24ed9bf8e572

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

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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-476NULL Pointer Dereference
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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