CVE-2021-47027

Kernel panic via unreleased IRQ before vector cleanup

Published Feb 28, 2024 · Updated May 11, 2026

Improper cleanup in Linux 5.12 through 5.12.3 allows local users to trigger a kernel panic when MT7921 firmware loading fails. The mt7921_pci_probe error path freed the device after mt7921_register_device failed but left its managed IRQ registered before releasing PCI IRQ vectors. Systems require an MT7921 PCIe adapter and missing or failed firmware; the resulting free_msi_irqs BUG stops the host.

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

Improper cleanup in Linux 5.12 through 5.12.3 allows local users to trigger a kernel panic when MT7921 firmware loading fails. The mt7921_pci_probe error path freed the device after mt7921_register_device failed but left its managed IRQ registered before releasing PCI IRQ vectors. Systems require an MT7921 PCIe adapter and missing or failed firmware; the resulting free_msi_irqs BUG stops the host.

The record

CVE
CVE-2021-47027
Published
Feb 28, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 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=5.12
  2. Affected versionversion=5c14a5f944b91371961548b1907802f74a4d2e5c <a46b536cd60c0dbd4bf767c62a8774dec52bf099
  3. Affected versionversion=5c14a5f944b91371961548b1907802f74a4d2e5c <e230f0c44f011f3270680a506b19b7e84c5e8923

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=5c14a5f944b91371961548b1907802f74a4d2e5c <a46b536cd60c0dbd4bf767c62a8774dec52bf099; version=5c14a5f944b91371961548b1907802f74a4d2e5c <e230f0c44f011f3270680a506b19b7e84c5e8923

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5CanonicalCVSS: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

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

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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