The support thing here is just an illustrative example of one of the many features you might build that could result in an MCP with read access to your database being exposed to malicious inputs.
Here are some more:
- a comments system, where users can post comments on articles
- a "feedback on this feature" system where feedback is logged to a database
- web analytics that records the user-agent or HTTP referrer to a database table
- error analytics where logged stack traces might include data a user entered
- any feature at all where a user enters freeform text that gets recorded in a database - that's most applications you might build!
The support system example is interesting in that it also exposes a data exfiltration route, if the MCP has write access too: an attack can ask it to write stolen data back into that support table as a support reply, which will then be visible to the attacker via the support interface.