Editing SQL injection (section)

===Second-order SQL injection===
Second-order SQL injection occurs when an application only guards its SQL against immediate user input, but has a less strict policy when dealing with data already stored in the system. Therefore, although such application would manage to safely process the user input and store it without issue, it would store the malicious SQL statement as well. Then, when another part of that application would use that data in a query that isn't protected from SQL injection, this malicious statement might get executed.{{Citation needed|date=March 2025}} This attack requires more knowledge of how submitted values are later used.  Automated web application security scanners would not easily detect this type of SQL injection and may need to be manually instructed where to check for evidence that it is being attempted.

In order to protect from this kind of attack, all SQL processing must be uniformly secure, despite the data source.