CVE-2021-47394

Local privilege escalation via lockless table lookup

Published May 21, 2024 · Updated Aug 5, 2026

Use-after-free in Linux kernel 5.12 through 5.14.9 allows local users to elevate privileges or crash the system via nf_tables operations. During owned-table deletion, nft_table_lookup performs lockless GET access while the table remains linked after synchronization, allowing a concurrent request to dereference freed memory. A local user can create a user and network namespace to obtain the required namespace capability; successful exploitation enables kernel memory access or a kernel panic.

CVSS severity7.8
High
EPSS probability0.23%
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 5.12 through 5.14.9 allows local users to elevate privileges or crash the system via nf_tables operations. During owned-table deletion, nft_table_lookup performs lockless GET access while the table remains linked after synchronization, allowing a concurrent request to dereference freed memory. A local user can create a user and network namespace to obtain the required namespace capability; successful exploitation enables kernel memory access or a kernel panic.

The record

CVE
CVE-2021-47394
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
Unavailable

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=5.12
  2. Affected versionversion=6001a930ce0378b62210d4f83583fc88a903d89d <a499b03bf36b0c2e3b958a381d828678ab0ffc5e
  3. Affected versionversion=6001a930ce0378b62210d4f83583fc88a903d89d <f65c73d3aabb87d4353e0bc4a718b5ae8c43fd04

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=6001a930ce0378b62210d4f83583fc88a903d89d <a499b03bf36b0c2e3b958a381d828678ab0ffc5e; version=6001a930ce0378b62210d4f83583fc88a903d89d <f65c73d3aabb87d4353e0bc4a718b5ae8c43fd04

Published CVSS scores

7.8OSVCVSS: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 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

T1068Exploitation for Privilege Escalation

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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