In wnpa-sec-2013-64 · ActiveMQ OpenWire dissector large loop :platform :x86 windows 7.

"x86" is a term that's used for a couple of purposes:

1. It can refer to the 16-bit, 32-bit, and 64-bit instruction set architectures for Intel's main line of processors and the compatible processors from companies such as AMD, Via, etc..
2. It can refer to the 32-bit version, with "AMD64", "x86-64", or "x64" used to refer to the 64-bit version.

In this case, it happens to refer to the second meaning. However, the Wireshark page about that vulnerability doesn't mention the platform, because the vulnerability happens to apply to ALL platforms; that page links to Wireshark bug 9248, which is the Wireshark bug database for that vulnerability, and the person who reported that bug happened to be running the 32-bit version of Wireshark on WIndows, so that bug gives the platform as x86 Windows 7, but it's also a bug on x64 (64-bit) Windows 7), and 32-bit and 64-bit Windows XP, and 32-bit and 64-bit Windows Vista, and 32-bit and 64-bit OS X, and Linux on 32-bit and 64-bit Intel and ARM and System/3x0 and PowerPC and SPARC and MIPS and....