CVE-2021-45117Public exploitNetwork attack vector

Application crash via unexpected response status

Published Mar 21, 2022 · Updated Aug 4, 2024

NULL pointer dereference in OPC Foundation ANSI C stack stubs allows remote attackers to crash OPC UA client applications. Generated synchronous Client API code dereferences a null pointer when it reads an unexpected status code from an OPC UA response message. The client must connect to a malicious server or receive packets manipulated by man-in-the-middle attackers; the failure crashes the client component and can also affect servers that invoke OpcUa_ClientApi_RegisterServer.

CVSS severity6.5
Medium
EPSS probability1.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

NULL pointer dereference in OPC Foundation ANSI C stack stubs allows remote attackers to crash OPC UA client applications. Generated synchronous Client API code dereferences a null pointer when it reads an unexpected status code from an OPC UA response message. The client must connect to a malicious server or receive packets manipulated by man-in-the-middle attackers; the failure crashes the client component and can also affect servers that invoke OpcUa_ClientApi_RegisterServer.

The record

CVE
CVE-2021-45117
Published
Mar 21, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 21, 2022CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

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

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.0OPC FoundationCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H/E:F/RL:O/RC:C
4.3NIST NVDAV:N/AC:M/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo