CVE-2021-47056

Kernel crash via premature device-running flag

Published Feb 29, 2024 · Updated May 11, 2026

Use of an uninitialized resource in the Linux QAT virtual-function driver allows local users to crash the kernel during device shutdown. The driver sets ADF_STATUS_PF_RUNNING before adf_dev_init succeeds, so shutdown can pass an uninitialized or destroyed vf2pf_lock to mutex_lock. Reachability requires Intel QAT virtual-function hardware, failed device initialization, and subsequent probe shutdown; the bounded consequence is a kernel crash.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use of an uninitialized resource in the Linux QAT virtual-function driver allows local users to crash the kernel during device shutdown. The driver sets ADF_STATUS_PF_RUNNING before adf_dev_init succeeds, so shutdown can pass an uninitialized or destroyed vf2pf_lock to mutex_lock. Reachability requires Intel QAT virtual-function hardware, failed device initialization, and subsequent probe shutdown; the bounded consequence is a kernel crash.

The record

CVE
CVE-2021-47056
Published
Feb 29, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-908, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 29, 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=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <05ec8192ee4bfdf2a8894a68350dac9f1a155fa6
  2. Affected versionversion=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <09d16cee6285d37cc76311c29add6d97a7e4acda
  3. Affected versionversion=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <1ea500ce6f7c9106e4a561d28e69215f3d451818
  4. Affected versionversion=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <1f50392650ae794a1aea41c213c6a3e1c824413c
  5. Affected versionversion=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <20fd40fc6f2c2b41dc6f637f88d494b14e9c21f1
  6. Affected versionversion=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <446045cf682af12d9294765f6c46084b374b5654
  7. Affected versionversion=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <8609f5cfdc872fc3a462efa6a3eca5cb1e2f6446
  8. Affected versionversion=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <f4c4e07140687f42bfa40e091bb4a55d7960ce4d
  9. Affected versionversion=4.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <05ec8192ee4bfdf2a8894a68350dac9f1a155fa6; version=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <09d16cee6285d37cc76311c29add6d97a7e4acda; version=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <1ea500ce6f7c9106e4a561d28e69215f3d451818; version=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <1f50392650ae794a1aea41c213c6a3e1c824413c; version=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <20fd40fc6f2c2b41dc6f637f88d494b14e9c21f1; version=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <446045cf682af12d9294765f6c46084b374b5654; version=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <8609f5cfdc872fc3a462efa6a3eca5cb1e2f6446; version=25c6ffb249f612c56a48ce48a3887adf57b8f4bd <f4c4e07140687f42bfa40e091bb4a55d7960ce4d; version=4.7

Published CVSS scores

5.5NVDCVSS: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

CWE-908Use of Uninitialized Resource
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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