Sounds like it was a 'channel file' which I think is akin to an av definition file that caused the problem rather than an actual software change. So they must have had a bug lurking in their kernel driver which was uncovered by a particular channel file. Still, seems like someone skipped some testing.
How about a try-catch block? The software reading the definition file should be minimally resilient against malformed input. That's like programming 101.