Here, Let me fix that for you

Java, Flash, and Silverlight were insecure platform specific NPAPI plugins that make it easy to p0wn users machines.

PNaCl uses PPAPI that together are designed from the ground up to be portable and secure. PPAPI provides the only APIs NaCL apps can call. They are cross platform so you write 1 plugin and it runs on Linux/OSX/Windows. Compare to NPAPI where the plugin has to be custom for each platform and calls into the OS directly unrestricted.

Actually, Silverlight is a pretty secure platform: out of 10 listed [1] vulnerabilities only 7 execute code and 2 gain admin access on the machine.

Here's how Flash player looks like: [2]

And here's Chrome's track of record: [3] (unfortunately, there's no good way to filter out NaCl defects)

[1] http://www.cvedetails.com/vulnerability-list/vendor_id-26/pr...

[2] http://www.cvedetails.com/vulnerability-list/vendor_id-53/pr...

[3] http://www.cvedetails.com/product/15031/Google-Chrome.html?v...