CVE-2021-47351

Local privilege escalation via UBIFS xattr race

Published May 21, 2024 · Updated Aug 5, 2026

Race condition in Linux UBIFS allows local users to corrupt kernel memory through concurrent extended-attribute operations. The listxattr path sizes its kvmalloc buffer before a second xattr traversal, while concurrent setxattr activity can change the list without per-inode serialization and cause names to be copied past the allocation. Reachability requires unprivileged local write access to a mounted UBIFS volume; the race allows kernel-memory disclosure or corruption, privilege escalation, stale values, or a kernel crash.

CVSS severityUnavailable
Unscored
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

Race condition in Linux UBIFS allows local users to corrupt kernel memory through concurrent extended-attribute operations. The listxattr path sizes its kvmalloc buffer before a second xattr traversal, while concurrent setxattr activity can change the list without per-inode serialization and cause names to be copied past the allocation. Reachability requires unprivileged local write access to a mounted UBIFS volume; the race allows kernel-memory disclosure or corruption, privilege escalation, stale values, or a kernel crash.

The record

CVE
CVE-2021-47351
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
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=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <38dde03eb239605f428f3f1e4baa73d4933a4cc6
  2. Affected versionversion=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <7adc05b73d91a5e3d4ca7714fa53ad9b70c53d08
  3. Affected versionversion=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <9558612cb829f2c022b788f55d6b8437d5234a82
  4. Affected versionversion=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <c0756f75c22149d20fcb7d8409827cee905eb386
  5. Affected versionversion=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <f4e3634a3b642225a530c292fdb1e8a4007507f5
  6. Affected versionversion=2.6.27

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <38dde03eb239605f428f3f1e4baa73d4933a4cc6; version=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <7adc05b73d91a5e3d4ca7714fa53ad9b70c53d08; version=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <9558612cb829f2c022b788f55d6b8437d5234a82; version=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <c0756f75c22149d20fcb7d8409827cee905eb386; version=1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d <f4e3634a3b642225a530c292fdb1e8a4007507f5; version=2.6.27

Published CVSS scores

No CVSS assessment is available in this record.

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

T1068Exploitation for Privilege Escalation

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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