[muglug]

It's explained in the article:

> We also use the traditional security programs to measure missed bugs (that is, the vulnerabilities for which there is a Zoncolan category), but the tool failed to report them. To date, we have had about 11 missed bugs, some of them caused by a bug in the tool or incomplete modeling.

A missed bug is presumably one that the tool is designed to spot, but which it didn't during the period in which it has been running.