CVE-2021-47339

Kernel-data disclosure via uncleared V4L2 ioctl buffers

Published May 21, 2024 · Updated May 11, 2026

Use of uninitialized data in Linux 5.11 through 5.12.17 and 5.13 through 5.13.2 allows local users to trigger stale data via V4L2 ioctls. The video_get_user function passes an uncleared ioctl buffer to compat and time32 conversion handlers, leaving uninitialized stack bytes available to driver ioctl handlers. Reaching the flaw requires local access to a V4L2 device; affected drivers can process stale kernel data and expose it indirectly.

CVSS severity5.5
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use of uninitialized data in Linux 5.11 through 5.12.17 and 5.13 through 5.13.2 allows local users to trigger stale data via V4L2 ioctls. The video_get_user function passes an uncleared ioctl buffer to compat and time32 conversion handlers, leaving uninitialized stack bytes available to driver ioctl handlers. Reaching the flaw requires local access to a V4L2 device; affected drivers can process stale kernel data and expose it indirectly.

The record

CVE
CVE-2021-47339
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-908
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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=5.11
  2. Affected versionversion=8dbcc3fa387c16abfc88a628cf528c439c91b332 <7b53cca764f9b291b7907fcd39d9e66ad728ee0b
  3. Affected versionversion=8dbcc3fa387c16abfc88a628cf528c439c91b332 <bfb48b54db25c3b4ef4bef5e0691464ebc4aa335
  4. Affected versionversion=8dbcc3fa387c16abfc88a628cf528c439c91b332 <dc02c0b2bd6096f2f3ce63e1fc317aeda05f74d8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.11; version=8dbcc3fa387c16abfc88a628cf528c439c91b332 <7b53cca764f9b291b7907fcd39d9e66ad728ee0b; version=8dbcc3fa387c16abfc88a628cf528c439c91b332 <bfb48b54db25c3b4ef4bef5e0691464ebc4aa335; version=8dbcc3fa387c16abfc88a628cf528c439c91b332 <dc02c0b2bd6096f2f3ce63e1fc317aeda05f74d8

Published CVSS scores

5.5NISTCVSS: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

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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