Understanding vc2013redistx86 (Version 12.0.40664.0): The Visual C++ 2013 x86 Runtime Introduction In the ecosystem of Windows software, few components are as ubiquitous yet misunderstood as the Visual C++ Redistributable packages. Among these, vc2013redistx86 (referring to the Visual C++ 2013 Redistributable for x86 architectures ) is a critical system component. This article focuses specifically on file version 12.0.40664.0 — a relatively late update to the 2013 runtime — and explains its purpose, technical details, and why it matters for both developers and end users. What Is vc2013redistx86? The vc2013redistx86 package installs runtime components of Microsoft Visual C++ 2013 required to run 32-bit (x86) applications developed with this version of the compiler. Even on modern 64-bit versions of Windows, many legacy and specialized applications still run as 32-bit processes, necessitating the x86 runtime. Without this redistributable, applications compiled with Visual C++ 2013 would fail to launch, typically displaying an error such as:
"The program can't start because MSVCR120.dll is missing from your computer."
The naming breakdown:
vc2013 = Visual C++ 2013 (internal version 12.0) redist = Redistributable package x86 = Targets 32-bit Windows/x86 processors (also runs on x64 via WoW64) vc2013redistx86 visual c 2013 x86 120 40664
The Specific Version: 12.0.40664.0 File version 12.0.40664.0 corresponds to a security and reliability update released in July 2016 (as part of Microsoft security bulletin MS16-100). It is not the original release (12.0.21005) nor the initial "Update 1" but rather a cumulative servicing update. Key characteristics of this version: | Attribute | Details | |-----------|---------| | Full version string | 12.0.40664.0 | | Core DLLs | msvcr120.dll, msvcp120.dll, vcomp120.dll, etc. | | Architecture | x86 (32-bit) | | Typical file size | ~9–12 MB (installer) | | Release date | July 12, 2016 | | Update classification | Security update / Hotfix rollup | Why This Version Matters
Security fixes – This update patches vulnerabilities in the C++ runtime libraries, including potential remote code execution flaws in the Microsoft Foundation Classes (MFC) and the C runtime I/O functions.
Bug fixes – Addresses several stability issues, including memory leaks in certain threading scenarios and incorrect exception handling in specific edge cases. Understanding vc2013redistx86 (Version 12
Backward compatibility – Applications built with older versions of Visual C++ 2013 (e.g., original RTM or earlier updates) will continue to work after installing 12.0.40664.0, as the runtime uses a versioned file system (side-by-side assembly via WinSxS) or direct binary compatibility.
Technical Components After installation, the following key files are placed in C:\Windows\System32 (on 32-bit Windows) or C:\Windows\SysWOW64 (on 64-bit Windows, for 32-bit app compatibility): | Filename | Description | Version in this update | |----------|-------------|------------------------| | msvcr120.dll | C Runtime Library | 12.0.40664.0 | | msvcp120.dll | C++ Standard Library | 12.0.40664.0 | | vcomp120.dll | OpenMP support | 12.0.40664.0 | | mfc120.dll | Microsoft Foundation Classes | 12.0.40664.0 | | mfcm120.dll | Managed MFC (C++/CLI) | 12.0.40664.0 | These binaries are digitally signed by Microsoft, ensuring authenticity. Installation and Deployment For End Users You rarely need to manually install version 12.0.40664.0. Most modern software installers either bundle the redistributable or download the latest available version from Microsoft. However, if you encounter missing DLL errors, you can:
Download the official redistributable (search for "Visual C++ Redistributable for Visual Studio 2013"). Run vcredist_x86.exe and follow the setup wizard. What Is vc2013redistx86
For System Administrators Silent installation with logging: vcredist_x86.exe /quiet /norestart /log install.log
Verification (check if the correct version is installed via registry): HKLM\SOFTWARE\Microsoft\VisualStudio\12.0\VC\Runtimes\x86 -> "Version" = "12.0.40664.0"