I was watching a defcon video a couple of weeks ago where a guy was demonstrating how barcode readers were generally quite easy to hack. He went on to say things such as with most systems the input isn't sanitised (sounds similar to SQL injection) and that most of them were configurable by bar codes easily obtained by the manufacturer. Combined with the fact that a machine can quickly be configured to read all types of barcodes including the ones that can store in excess of 1000 characters, are barcodes a vulnerability? And how could one prevent this?
So far the possible vulnerabilities I can see are SQL injection and buffer overflows.