CVE-2023-52891Network attack vector

Unauthenticated service blockage via repeated ConditionRefresh requests

Published Jul 9, 2024 · Updated Aug 27, 2025

Resource exhaustion in Siemens SIMATIC and SIMIT OPC UA servers allows remote attackers to block service with unauthenticated requests. The embedded Unified Automation .NET Server SDK handles repeated ConditionRefresh requests by allocating resources until memory and CPU capacity are exhausted. Network access to an enabled OPC UA interface is sufficient; no authentication or user interaction is required, and the reported consequence is server blockage rather than data disclosure or modification.

CVSS severity5.3
Medium
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

Resource exhaustion in Siemens SIMATIC and SIMIT OPC UA servers allows remote attackers to block service with unauthenticated requests. The embedded Unified Automation .NET Server SDK handles repeated ConditionRefresh requests by allocating resources until memory and CPU capacity are exhausted. Network access to an enabled OPC UA interface is sufficient; no authentication or user interaction is required, and the reported consequence is server blockage rather than data disclosure or modification.

The record

CVE
CVE-2023-52891
Published
Jul 9, 2024
Updated
Aug 27, 2025
Vendor
Siemens
Product
SIMATIC Energy Manager PRO
Classifications
CWE-1325, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 9, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 2025Record 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=0 <V7.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC Energy Manager PROversion=0 <V7.5
Siemens · SIMITversion=0 <=*; version=0 <*; version=0 <V11.1
Siemens · SIMATIC IPC DiagMonitorversion=0 <=*; version=0 <*
Siemens · SIMATIC IPC DiagBaseversion=0 <=*; version=0 <*
Siemens · SIMATIC Energy Manager Basicversion=0 <V7.5

Published CVSS scores

5.3Siemens ProductCERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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-1325Improperly Controlled Sequential Memory Allocation
T1499Endpoint Denial 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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