CVE-2021-42976Public exploit

Kernel code execution via unchecked IOCTL copy sizes

Published Dec 7, 2021 · Updated Aug 4, 2024

A buffer overflow in NoMachine Enterprise Desktop after 4.0.346 and before 7.7.4 allows local users to execute code in kernel mode. IOCTL handler 0x22001B accepts a METHOD_NEITHER user buffer, derives allocation and memmove sizes independently from user-controlled fields, and performs unchecked arithmetic that permits the copy to exceed the allocated kernel buffer. The driver exposes the IOCTL without an access-control restriction, allowing an unprivileged local process to corrupt kernel memory, execute kernel-mode code, or crash the operating system.

CVSS severity8.8
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A buffer overflow in NoMachine Enterprise Desktop after 4.0.346 and before 7.7.4 allows local users to execute code in kernel mode. IOCTL handler 0x22001B accepts a METHOD_NEITHER user buffer, derives allocation and memmove sizes independently from user-controlled fields, and performs unchecked arithmetic that permits the copy to exceed the allocated kernel buffer. The driver exposes the IOCTL without an access-control restriction, allowing an unprivileged local process to corrupt kernel memory, execute kernel-mode code, or crash the operating system.

The record

CVE
CVE-2021-42976
Published
Dec 7, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C
8.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1068Exploitation for Privilege Escalation

Public exploit references

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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