If an application is forced to run specifically on .NET 4.0 RTM (not a later in-place update), it remains vulnerable to the following high-impact CVEs:
Microsoft .NET Framework 4.0, which uses Common Language Runtime (CLR) version , is considered End of Life (EOL) . This version no longer receives security updates, technical support, or hotfixes from Microsoft. Key Security Risks & Vulnerabilities
Don't rely on the "4.0.30319" folder name or header. Instead, verify the specific version of the .NET Framework installed on your machine.
"Maybe," Elena replied, "but 'maybe' is how breaches start."