CVE-2021-47039

Memory disclosure and crash via unchecked format type

Published Feb 28, 2024 · Updated May 11, 2026

Out-of-bounds read in Linux kernel 5.11 through 5.11.20 and 5.12 through 5.12.3 allows local users to read kernel memory or crash the system. In drivers/block/ataflop.c, do_format() indexes unit[drive].disk[type] and dereferences its queue before rejecting an out-of-range media-format type. Reaching the flaw requires local access to the Atari floppy formatting ioctl on a kernel built for M68k Atari hardware with the ataflop driver.

CVSS severity7.1
High
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

Out-of-bounds read in Linux kernel 5.11 through 5.11.20 and 5.12 through 5.12.3 allows local users to read kernel memory or crash the system. In drivers/block/ataflop.c, do_format() indexes unit[drive].disk[type] and dereferences its queue before rejecting an out-of-range media-format type. Reaching the flaw requires local access to the Atari floppy formatting ioctl on a kernel built for M68k Atari hardware with the ataflop driver.

The record

CVE
CVE-2021-47039
Published
Feb 28, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-125
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=5.11
  2. Affected versionversion=bf9c0538e485b591a2ee02d9adb8a99db4be5a2a <07f86aa8f4fe077be1b018cc177eb8c6573e5671
  3. Affected versionversion=bf9c0538e485b591a2ee02d9adb8a99db4be5a2a <1ffec389a6431782a8a28805830b6fae9bf00af1
  4. Affected versionversion=bf9c0538e485b591a2ee02d9adb8a99db4be5a2a <2a3a8bbca28b899806844c00d49ed1b7ccb50957

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.11; version=bf9c0538e485b591a2ee02d9adb8a99db4be5a2a <07f86aa8f4fe077be1b018cc177eb8c6573e5671; version=bf9c0538e485b591a2ee02d9adb8a99db4be5a2a <1ffec389a6431782a8a28805830b6fae9bf00af1; version=bf9c0538e485b591a2ee02d9adb8a99db4be5a2a <2a3a8bbca28b899806844c00d49ed1b7ccb50957

Published CVSS scores

7.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
4.4SUSECVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N

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-125Out-of-bounds Read

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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