Microsoft Net Framework 4.0 V — 30319 Vulnerabilities

Microsoft .NET Framework 4.0, with its specific build version 4.0.30319, was a landmark release in Microsoft’s software development platform. Released alongside Visual Studio 2010 and Windows Server 2008 R2, it introduced significant improvements in parallel computing, managed extensibility, and the Core Common Language Runtime (CLR).

However, version 4.0.30319 is now considered legacy and out-of-support (mainstream support ended in 2016, extended support ended in 2021). As a result, unpatched installations of this exact version contain numerous critical vulnerabilities that expose systems to remote code execution, privilege escalation, and denial-of-service attacks.

Important Note: The version string 4.0.30319 refers to the CLR build number. This same base version appears across Windows 7, Windows Server 2008 R2, and later OSes—but the vulnerability status depends entirely on the patch level (update rollup) applied to that build.

There is no "silver bullet" for securing an unsupported runtime, but a layered approach can reduce risk:

| CVE ID | Vulnerability | CVSS Score (Base) | |--------|---------------|------------------| | CVE-2017-0248 | .NET Framework Security Feature Bypass (Insecure deserialization in remoting) | 7.8 (High) | | CVE-2012-1895 | .NET Framework Remoting Elevation of Privilege | 9.1 (Critical) | microsoft net framework 4.0 v 30319 vulnerabilities

Description: Unpatched .NET Remoting endpoints (TCP or HTTP channels) allow an unauthenticated attacker to send a crafted serialized object that, when deserialized by the framework, executes arbitrary code with the permissions of the hosting process (often SYSTEM for IIS-hosted apps).

Affected in 4.0.30319: The BinaryFormatter, SoapFormatter, and NetDataContractSerializer lacked proper type filtering prior to security updates.

Perhaps the most alarming finding is CVE-2020-1046 (and its variants), which affects the way v4.0.30319 handles URL redirects in the HttpWebRequest object. By combining this with a lack of proper TLS certificate validation in older builds, an attacker performing a man-in-the-middle (MitM) attack could redirect a .NET application to a malicious update server or a UNC path (\\evil\share\malicious.dll) leading to RCE.

Vulnerabilities in the Common Language Runtime (CLR) can allow an attacker to bypass security mechanisms. Microsoft

Severity: 7.4 (High)
Vector: Remote Code Execution

ClickOnce deployment in .NET 4.0.30319 did not enforce HTTPS for manifest downloads correctly. An attacker on the same local network (or via ARP spoofing) could replace a legitimate .application manifest with a malicious one. The .NET Framework would trust the manifest if the signature was still valid—even if the content changed.

Real-world: This allowed attackers to push trojaned updates to enterprise internal tools.

Severity: 7.8 (High)
Vector: Denial of Service leading to RCE Important Note: The version string 4

This is an obscure but severe flaw in how System.Data.DataView processes row filter expressions. If an application allows user input to affect a row filter string without sanitization, an attacker can inject specially crafted expressions that cause memory corruption.

Vulnerable components:

Microsoft patched this in December 2018. Unpatched 4.0.30319 systems remain at risk.