CVE-2021-4202

Local privilege escalation via NFC race

Published Mar 25, 2022 · Updated Aug 3, 2024

Use-after-free in Linux Kernel nci_request allows local users to escalate privileges via a race during NFC device removal. The nci_request function can access NCI data after concurrent device teardown frees it, creating a use-after-free condition. Local users need access to NFC functionality and device-removal timing; exploitation can crash the system or execute code with elevated kernel privileges.

CVSS severity7.0
High
EPSS probability0.36%
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 nci_request allows local users to escalate privileges via a race during NFC device removal. The nci_request function can access NCI data after concurrent device teardown frees it, creating a use-after-free condition. Local users need access to NFC functionality and device-removal timing; exploitation can crash the system or execute code with elevated kernel privileges.

The record

CVE
CVE-2021-4202
Published
Mar 25, 2022
Updated
Aug 3, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, CWE-362, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 25, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=kernel 5.16 rc2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=kernel 5.16 rc2

Published CVSS scores

7.0NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
6.9NVDAV:L/AC:M/Au:N/C:C/I:C/A:C

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

CWE-416Use After Free
CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
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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