CVE-2021-47338

System crash via in-use framebuffer mode deletion

Published May 21, 2024 · Updated Aug 5, 2026

Use-after-free in Linux kernel fbmem allows local users to crash affected 5.3 through 5.14-rc1 kernels via framebuffer ioctls. fb_set_var calls fb_delete_videomode even when fbcon_mode_deleted reports that the mode remains in use, leaving fb_display entries pointing to freed memory. Access to a framebuffer device is required; later mode comparison dereferences the stale pointer and can panic the host.

CVSS severity7.8
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux kernel fbmem allows local users to crash affected 5.3 through 5.14-rc1 kernels via framebuffer ioctls. fb_set_var calls fb_delete_videomode even when fbcon_mode_deleted reports that the mode remains in use, leaving fb_display entries pointing to freed memory. Access to a framebuffer device is required; later mode comparison dereferences the stale pointer and can panic the host.

The record

CVE
CVE-2021-47338
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=13ff178ccd6d3b8074c542a911300b79c4eec255 <087bff9acd2ec6db3f61aceb3224bde90fe0f7f8
  2. Affected versionversion=13ff178ccd6d3b8074c542a911300b79c4eec255 <0af778269a522c988ef0b4188556aba97fb420cc
  3. Affected versionversion=13ff178ccd6d3b8074c542a911300b79c4eec255 <359311b85ebec7c07c3a08ae2f3def946cad33fa
  4. Affected versionversion=13ff178ccd6d3b8074c542a911300b79c4eec255 <d6e76469157d8f240e5dec6f8411aa8d306b1126
  5. Affected versionversion=13ff178ccd6d3b8074c542a911300b79c4eec255 <f193509afc7ff37a46862610c93b896044d5b693
  6. Affected versionversion=5.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=13ff178ccd6d3b8074c542a911300b79c4eec255 <087bff9acd2ec6db3f61aceb3224bde90fe0f7f8; version=13ff178ccd6d3b8074c542a911300b79c4eec255 <0af778269a522c988ef0b4188556aba97fb420cc; version=13ff178ccd6d3b8074c542a911300b79c4eec255 <359311b85ebec7c07c3a08ae2f3def946cad33fa; version=13ff178ccd6d3b8074c542a911300b79c4eec255 <d6e76469157d8f240e5dec6f8411aa8d306b1126; version=13ff178ccd6d3b8074c542a911300b79c4eec255 <f193509afc7ff37a46862610c93b896044d5b693; version=5.3

Published CVSS scores

7.8Linux kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application 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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