Understanding what this string actually represents is critical before reacting to these security scanner reports. The Scanning Illusion: Framework vs. CLR Version
The patch for CVE-2017-8759 was backported to .NET 4.0 via the October 2017 Security and Quality Rollup. Any system still on original RTM or an early 4.0 build is completely exposed. This exploit was famously used by the FIN7 (Carbanak) gang to deliver DNSMessenger malware.
If this version is so insecure, why is it still present? Three primary reasons:
This allowed attackers to push trojaned updates to enterprise internal tools.
: An attacker can use specially crafted usernames to trick the subsystem, manipulate authentication tokens, and hijack high-privileged accounts. 2. Remote Code Execution via Array Copying (CVE-2011-3416) microsoft net framework 4.0 v 30319 vulnerabilities
While the CLR version number is not the issue, the underlying .NET Framework 4.0 is a different story.
Outdated installations of .NET Framework 4.0 are susceptible to several classes of exploits. Attackers frequently target these flaws to compromise enterprise web servers and windows endpoints. 1. Remote Code Execution (RCE)
| CVE ID | Vulnerability | CVSS Score (Base) | |--------|---------------|------------------| | | .NET Framework Security Feature Bypass (Insecure deserialization in remoting) | 7.8 (High) | | CVE-2012-1895 | .NET Framework Remoting Elevation of Privilege | 9.1 (Critical) |
However, in the cybersecurity world, "legacy" is often a synonym for "risk." While version 4.0.30319 is robust, it is no longer the latest. Microsoft has since released 4.5, 4.6, 4.7, and 4.8. Consequently, running an application strictly on the base build (without subsequent in-place updates) exposes organizations to a growing list of documented and weaponized vulnerabilities. Any system still on original RTM or an early 4
Use tools like or Microsoft’s own .NET Framework Repair Tool to scan installed applications for references to v4.0.30319 in their config files.
Maintaining an up-to-date system is critical. Ensure that you regularly install the latest from Microsoft. These cumulative updates contain all past security fixes and are readily available via Windows Update, WSUS (Windows Server Update Services), and the Microsoft Update Catalog.
The CLR serves as the underlying execution engine that compiles and runs .NET code. Microsoft introduced CLR 4.0 alongside .NET Framework 4.0. Crucially, Microsoft maintained this exact same CLR engine version for all subsequent releases in the .NET 4.x lineage, spanning from version 4.5 up to the final release, .NET Framework 4.8.1.
Many organizations struggle to eliminate .NET 4.0 risks due to several operational hurdles: Three primary reasons: This allowed attackers to push
The identifier is one of the most frequently flagged version strings in automated vulnerability scans. When automated security scanners crawl an application, they look at HTTP response headers like X-AspNet-Version . If they see 4.0.30319 , they often generate high-severity alerts for severe bugs like Remote Code Execution (RCE) or Authentication Bypass .
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later.
Despite its advancements, .NET Framework 4.0 has been found to have several vulnerabilities. These vulnerabilities can be exploited by attackers to gain unauthorized access to systems, execute arbitrary code, or elevate privileges. Some of the notable vulnerabilities include:
Ban the use of BinaryFormatter . Replace it with safer text-based serializers like System.Text.Json , ensuring type handling is strictly locked down.
If an environment runs the product from 2010 rather than a newer 4.x runtime, it faces several high-severity security threats. Microsoft ended support for the standalone .NET Framework 4.0 package in 2016, leaving unpatched instances exposed to several classic attack vectors: 1. Remote Code Execution (RCE) via Deserialization
Microsoft intends .NET 4.8 to be the final version of the classic .NET Framework. It is fully backward compatible with 4.0 applications.