In my entire experience as a software security practitioner, which at the time of my testimony encompassed some hundreds of assessments of SQL-backed websites, the availability of a schema has never impacted my ability to exploit a SQL injection. It's not my job as an expert witness, nor Matt's job as a plaintiff, to invent improbable scenarios where security could hinge on schema availability. The court (all of them, in fact) found that testimony dispositive, so I'm happy to leave the issue there.

"Blind" SQLi is a thing, but even in the real-life example I could find, it wasn't exactly blind. They could still use the timing to get one bit of info at a time and discern the email addresses. https://www.invokesec.com/2025/01/13/a-real-world-example-of...

It's hard to imagine a case where you can't even get info based on timing. But it requires more effort and knowledge to exploit this.

Not just that, but perhaps the app is smart enough to lock you out the second it detects an attempt to gather the schema, e.g. by logging and automatically responding to a query that displays the schema. Then you have to look for other ways in (another IP, etc.). But if you know the schema in advance, you have a better chance of a one-shot injection that accomplishes your malicious goal.

In other words, advance knowledge of the schema may make it easier to act maliciously.

I don’t think that’s a very common setup but perhaps I’m just exposing my own ignorance. Just consider the popularity of ORMs. They explicitly load the schema into the application in many cases.