CVE-2021-47055

Flash-state corruption via read-only MTD ioctls

Published Feb 29, 2024 · Updated Aug 5, 2026

Improper access control in affected Linux kernel releases allows local users to corrupt flash state through read-only descriptors. The mtdchar_ioctl path accepts MEMLOCK, MEMUNLOCK, OTPLOCK, and MEMSETBADBLOCK without FMODE_WRITE, allowing read-only opens to change protection bits or the bad-block table. Access to a readable /dev/mtdX or /dev/mtdXro node is required; resulting changes remove write protection, permanently lock regions, or make storage unusable.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in affected Linux kernel releases allows local users to corrupt flash state through read-only descriptors. The mtdchar_ioctl path accepts MEMLOCK, MEMUNLOCK, OTPLOCK, and MEMSETBADBLOCK without FMODE_WRITE, allowing read-only opens to change protection bits or the bad-block table. Access to a readable /dev/mtdX or /dev/mtdXro node is required; resulting changes remove write protection, permanently lock regions, or make storage unusable.

The record

CVE
CVE-2021-47055
Published
Feb 29, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667, T1565.001
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Feb 29, 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=1c9f9125892a43901438bf704ada6b7019e2a884 <f4d28d8b9b0e7c4ae04214b8d7e0b0466ec6bcaf
  2. Affected versionversion=36a8b2f49235e63ab3f901fe12e1b6732f075c2e
  3. Affected versionversion=389c74c218d3b182e9cd767e98cee0e0fd0dabaa <f73b29819c6314c0ba8b7d5892dfb03487424bee
  4. Affected versionversion=4.14.194 <4.14.233
  5. Affected versionversion=4.19.139 <4.19.191
  6. Affected versionversion=4.4.233 <4.4.269
  7. Affected versionversion=4.9.233 <4.9.269
  8. Affected versionversion=5.4.58 <5.4.119
  9. Affected versionversion=5.7.15 <5.8
  10. Affected versionversion=5.8.1 <5.9
  11. Affected versionversion=583d42400532fbd6228b0254d7c732b771e4750d <9625b00cac6630479c0ff4b9fafa88bee636e1f0
  12. Affected versionversion=5.9
  13. Affected versionversion=9a53e8bd59d9f070505e51d3fd19606a270e6b93 <5880afefe0cb9b2d5e801816acd58bfe91a96981
  14. Affected versionversion=ab1a602a9cea98aa37b2e6851b168d2a2633a58d <75ed985bd6c8ac1d4e673e93ea9d96c9908c1d37
  15. Affected versionversion=eb3d82abc335624a5e8ecfb75aba0b684e2dc4db
  16. Affected versionversion=f7e6b19bc76471ba03725fe58e0c218a3d6266c3 <077259f5e777c3c8821f6b41dee709fcda27306b
  17. Affected versionversion=f7e6b19bc76471ba03725fe58e0c218a3d6266c3 <1e97743fd180981bef5f01402342bb54bf1c6366
  18. Affected versionversion=f7e6b19bc76471ba03725fe58e0c218a3d6266c3 <7b6552719c0ccbbea29dde4be141da54fdb5877e
  19. Affected versionversion=f7e6b19bc76471ba03725fe58e0c218a3d6266c3 <a08799d3e8c8088640956237c183f83463c39668

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=1c9f9125892a43901438bf704ada6b7019e2a884 <f4d28d8b9b0e7c4ae04214b8d7e0b0466ec6bcaf; version=36a8b2f49235e63ab3f901fe12e1b6732f075c2e; version=389c74c218d3b182e9cd767e98cee0e0fd0dabaa <f73b29819c6314c0ba8b7d5892dfb03487424bee; version=4.14.194 <4.14.233; version=4.19.139 <4.19.191; version=4.4.233 <4.4.269; version=4.9.233 <4.9.269; version=5.4.58 <5.4.119; version=5.7.15 <5.8; version=5.8.1 <5.9; version=583d42400532fbd6228b0254d7c732b771e4750d <9625b00cac6630479c0ff4b9fafa88bee636e1f0; version=5.9; version=9a53e8bd59d9f070505e51d3fd19606a270e6b93 <5880afefe0cb9b2d5e801816acd58bfe91a96981; version=ab1a602a9cea98aa37b2e6851b168d2a2633a58d <75ed985bd6c8ac1d4e673e93ea9d96c9908c1d37; version=eb3d82abc335624a5e8ecfb75aba0b684e2dc4db; version=f7e6b19bc76471ba03725fe58e0c218a3d6266c3 <077259f5e777c3c8821f6b41dee709fcda27306b; version=f7e6b19bc76471ba03725fe58e0c218a3d6266c3 <1e97743fd180981bef5f01402342bb54bf1c6366; version=f7e6b19bc76471ba03725fe58e0c218a3d6266c3 <7b6552719c0ccbbea29dde4be141da54fdb5877e; version=f7e6b19bc76471ba03725fe58e0c218a3d6266c3 <a08799d3e8c8088640956237c183f83463c39668

Published CVSS scores

5.5NIST NVDCVSS: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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-667Improper Locking
T1565.001Stored Data Manipulation

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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