What is CVE-2021-42023?

CVE-2021-42023 is a medium-severity vulnerability in Siemens Modelsim, classified under Insufficiently Protected Credentials. CVSS score: 6.5/10. Published 2021-12-14.

How severe is CVE-2021-42023?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Siemens Modelsim

CVE-2021-42023

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.

Published 2021-12-14 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.006 (44.6th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 44.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Siemens Modelsim
Siemens Modelsim Simulation — versions All versions
Siemens Questa
Siemens Questa Simulation — versions All versions

Weakness classification (CWE)

CWE-522 — Insufficiently Protected Credentials

References

cert-portal.siemens.com/productcert/pdf/ssa-400332.pdf (Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2021-42023?: CVE-2021-42023 is a medium-severity vulnerability in Siemens Modelsim, classified under Insufficiently Protected Credentials. CVSS score: 6.5/10. Published 2021-12-14.
How severe is CVE-2021-42023?: Medium severity. CVSS v3 base score is 6.5 out of 10.