CVE-2021-25673

Application hang via crafted project file

Published Mar 15, 2021 · Updated Aug 3, 2024

Infinite loop in Siemens SIMATIC S7-PLCSIM V5.4 allows local users to hang the application by opening a crafted project file. When the application opens the crafted project file, its processing enters a loop whose exit condition is unreachable. Local access and an application open operation are required; the process remains unresponsive until it is restarted.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in Siemens SIMATIC S7-PLCSIM V5.4 allows local users to hang the application by opening a crafted project file. When the application opens the crafted project file, its processing enters a loop whose exit condition is unreachable. Local access and an application open operation are required; the process remains unresponsive until it is restarted.

The record

CVE
CVE-2021-25673
Published
Mar 15, 2021
Updated
Aug 3, 2024
Vendor
Siemens
Product
SIMATIC S7-PLCSIM
Classifications
CWE-835, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=All versions

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Siemens · SIMATIC S7-PLCSIMversion=All versions

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.9NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:C

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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