CVE-2021-42983Public exploit

Kernel code execution via oversized IOCTL copy

Published Dec 7, 2021 · Updated Aug 4, 2024

Buffer overflow in NoMachine Enterprise Client after 4.0.346 and before 7.7.4 allows local users to execute kernel-mode code. IOCTL handler 0x22001B allocates a kernel pool buffer using one attacker-controlled size, then passes a separately controlled larger length to memmove. Any local user able to open the unprotected device can corrupt kernel memory, gain kernel privileges, or crash Windows.

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

Buffer overflow in NoMachine Enterprise Client after 4.0.346 and before 7.7.4 allows local users to execute kernel-mode code. IOCTL handler 0x22001B allocates a kernel pool buffer using one attacker-controlled size, then passes a separately controlled larger length to memmove. Any local user able to open the unprotected device can corrupt kernel memory, gain kernel privileges, or crash Windows.

The record

CVE
CVE-2021-42983
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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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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