# CVE-2025-40759: Deserialization in SIMATIC S7-PLCSIM V17

> Attackers can execute arbitrary code by exploiting improper sanitization of stored security properties when parsing project files in Siemens industrial automation tools.

- **Severity:** High 8.5 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 12 Aug 2025
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-hgv7-qqgv-vj6c

## What is CVE-2025-40759?

CVE-2025-40759 is a high-severity unsafe deserialization vulnerability in Siemens SIMATIC S7-PLCSIM V17, published on 12 Aug 2025. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

A vulnerability has been identified in SIMATIC S7-PLCSIM V17 (All versions), SIMATIC STEP 7 V17 (All versions < V17 Update 9), SIMATIC STEP 7 V18 (All versions < V18 Update 6), SIMATIC STEP 7 V19 (All versions < V19 Update 4), SIMATIC STEP 7 V20 (All versions < V20 Update 4), SIMATIC WinCC V17 (All versions < V17 Update 9), SIMATIC WinCC V18 (All versions < V18 Update 6), SIMATIC WinCC V19 (All versions < V19 Update 4), SIMATIC WinCC V20 (All versions < V20 Update 4), SIMOCODE ES V17 (All versions), SIMOCODE ES V18 (All versions), SIMOCODE ES V19 (All versions), SIMOCODE ES V20 (All versions), SIMOTION SCOUT TIA V5.4 (All versions), SIMOTION SCOUT TIA V5.5 (All versions), SIMOTION SCOUT TIA V5.6 (All versions < V5.6 SP1 HF7), SIMOTION SCOUT TIA V5.7 (All versions), SINAMICS Startdrive V17 (All versions), SINAMICS Startdrive V18 (All versions), SINAMICS Startdrive V19 (All versions), SINAMICS Startdrive V20 (All versions), SIRIUS Safety ES V17 (TIA Portal) (All versions), SIRIUS Safety ES V18 (TIA Portal) (All versions), SIRIUS Safety ES V19 (TIA Portal) (All versions), SIRIUS Safety ES V20 (TIA Portal) (All versions), SIRIUS Soft Starter ES V17 (TIA Portal) (All versions), SIRIUS Soft Starter ES V18 (TIA Portal) (All versions), SIRIUS Soft Starter ES V19 (TIA Portal) (All versions), SIRIUS Soft Starter ES V20 (TIA Portal) (All versions), TIA Portal Cloud V17 (All versions), TIA Portal Cloud V18 (All versions), TIA Portal Cloud V19 (All versions < V5.2.1.1), TIA Portal Cloud V20 (All versions < V5.2.2.2). Affected products do not properly sanitize stored security properties when parsing project files. This could allow an attacker to cause a type confusion and execute arbitrary code within the affected application.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2025-40759?


## How do I fix CVE-2025-40759?

No fix has been published for CVE-2025-40759 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-40759 being exploited?

There is no known exploitation of CVE-2025-40759 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40759 and fix it if it is affected.

What it is: CVE-2025-40759 is a high-severity unsafe deserialization vulnerability in Siemens SIMATIC S7-PLCSIM V17, published on 12 Aug 2025. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2025-40759 in the wild and no public exploit code.

Affected product: Siemens SIMATIC S7-PLCSIM V17. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-40759/ (Markdown: https://insights.sbomify.com/CVE-2025-40759/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40759
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40759
- OSV: https://osv.dev/vulnerability/CVE-2025-40759

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-40759/
Summaries are generated and may contain mistakes; the official description above is the record.