CVE-2021-36764Network attack vector

Unauthenticated service interruption via NULL pointer dereference

Published Aug 4, 2021 · Updated Aug 4, 2024

NULL pointer dereference in CODESYS Gateway V3 before 3.5.17.10 allows remote attackers to interrupt gateway service with crafted requests. The CmpGateway component routes online communication between engineering clients and runtime systems but dereferences a null pointer while processing a malformed communication request. No authentication or user interaction is required, and exploitation disrupts gateway availability without reported confidentiality or integrity impact.

CVSS severity7.5
High
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in CODESYS Gateway V3 before 3.5.17.10 allows remote attackers to interrupt gateway service with crafted requests. The CmpGateway component routes online communication between engineering clients and runtime systems but dereferences a null pointer while processing a malformed communication request. No authentication or user interaction is required, and exploitation disrupts gateway availability without reported confidentiality or integrity impact.

The record

CVE
CVE-2021-36764
Published
Aug 4, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5CODESYS GmbHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T0814Denial of Service

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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