CVE-2021-25675
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA vulnerability has been identified in SIMATIC S7-PLCSIM V5.4 (All versions). An attacker with local access to the system could cause a Denial-of-Service condition in the application when it is used to open a specially crafted file. As a consequence, a divide by zero operation could occur and cause the application to terminate unexpectedly and must be restarted to restore the service.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA divide-by-zero vulnerability exists in SIMATIC S7-PLCSIM V5.4 where opening a specially crafted file triggers the condition, causing the application to crash. The attacker requires local access to the system, making this a local denial-of-service vector rather than remote.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 5.4CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm SIMATIC S7-PLCSIM installationCheck if Siemens SIMATIC S7-PLCSIM is installed on the system by reviewing installed programs in Windows Control Panel > Programs and Features, or by searching for 'S7-PLCSIM' in the Start menu or program directories.Affected if The application is not installed on the system.
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Identify installed version numberLocate the installed version by right-clicking the S7-PLCSIM executable (typically found in the Siemens installation directory, such as C:\Program Files\Siemens\Automation\S7-PLCSIM or similar), selecting Properties, and reviewing the Details tab for the Version information. Alternatively, open S7-PLCSIM and check the Help > About menu for the exact version number.Affected if The displayed version is exactly 5.4 (the only affected version per vendor advisory).
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Verify file association handlingReview the system's file associations for project or simulation files related to S7-PLCSIM (common extensions include .s7p, .sim, or PLC-specific project files). Check if the application is configured to automatically open files upon double-click.Affected if S7-PLCSIM is installed at version 5.4 and handles file associations for the affected file types.
The system is vulnerable if SIMATIC S7-PLCSIM version 5.4 is installed, since this version contains the divide-by-zero flaw when processing specially crafted files.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUntil a vendor patch is released, restrict local access to the system and train users to avoid opening files from untrusted sources. Consider isolating the affected system or implementing application whitelisting to reduce exposure.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-25675 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-25675 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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