---
id: "CVE-2025-66969"
kind: "vulnerability"
aliases: ["CVE-2025-66969"]
title: "OpenModSim: integer overflow lets a crafted input crash it"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["industrial", "modbus", "openmodsim", "other"]
not_affected_if: ["unknown"]
published_at: "2026-10-16T19:16:57+00:00"
first_seen_at: "2026-10-23T21:57:14+00:00"
updated_at: "2026-10-25T03:24:56+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66969", "first_seen_at": "2026-10-23T21:57:14+00:00"}]
---

# OpenModSim: integer overflow lets a crafted input crash it

OpenModSim, a Modbus simulator, has an integer overflow in versions up to 1.11.0. Sending crafted input can cause a denial of service.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed OpenModSim version against `1.11.0` (unknown how the version is reported by the sources)
- Confirm whether the simulator is reachable from untrusted networks (unknown from the sources)

## Fix

- Move to a release newer than `1.11.0` once the vendor ships one (unknown from the sources)

## Timeline

- 2026-10-23T21:57:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2025-66969

## From the sources

Integer overflow in OpenModSim (<=1.11.0), leading to denial of service

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_