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CVE-2025-21426 — Windows MSHTML RCE

Key facts

CVE-2025-21426 is a Critical vulnerability: Windows MSHTML RCE. This entry ships a detection-only PoC.
CVE CVE-2025-21426
Severity Critical
Detection / prevention —
PoC poc.py
Source 2025/CVE-2025-21426/

Details

Overview

Windows MSHTML rce vulnerability

Details

  • CVE ID: CVE-2025-21426
  • CVSS Score: 9.8 (Critical)
  • Type: RCE
  • Product: Windows MSHTML

Usage

python3 poc.py -t https://target -c

References

Frequently asked questions

What is CVE-2025-21426?

CVE-2025-21426 is a Critical vulnerability: Windows MSHTML RCE. This entry ships a detection-only PoC.

How do I detect CVE-2025-21426?

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2025-21426?

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

For authorized security testing and research only. See the full source and NVD record.