CVE-2025-40797Network attack vector

Unauthenticated service crash via oversized Message 3

Published Sep 9, 2025 · Updated Jun 9, 2026

Out-of-bounds read in Siemens UMC and SIMATIC PCS neo allows remote attackers to crash um.Ris.exe with a crafted Message 3 integer. The Message 3 handler trusts an attacker-supplied large integer when reading memory, causing an invalid access that terminates the process. No authentication or user interaction is required; the reported consequence is loss of the UMC service, not code execution.

CVSS severity8.7
High
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Siemens UMC and SIMATIC PCS neo allows remote attackers to crash um.Ris.exe with a crafted Message 3 integer. The Message 3 handler trusts an attacker-supplied large integer when reading memory, causing an invalid access that terminates the process. No authentication or user interaction is required; the reported consequence is loss of the UMC service, not code execution.

The record

CVE
CVE-2025-40797
Published
Sep 9, 2025
Updated
Jun 9, 2026
Vendor
Siemens
Product
User Management Component (UMC)
Classifications
CWE-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 2026Record 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 <V2.15.1.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · User Management Component (UMC)version=0 <V2.15.1.3
Siemens · SIMATIC PCS neoversion=0 <*; version=0 <V6.0 SP1 Update 1

Published CVSS scores

7.5Siemens ProductCERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7Siemens ProductCERTCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

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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