CWE-1173 describes code that does not use, or incorrectly uses, an input validation framework that the language or an independent library already provides. It is a weakness about process as much as code. Nothing breaks on day one. The risk shows up when unchecked input reaches a place that trusts it.
Any team that accepts data from users, partners or other services can hit this. Web back ends are the usual case, but the pattern is language independent.
How it happens
Modern frameworks check input against declared rules and send bad input to an error handler automatically. MITRE notes that these frameworks make validation easier and less error prone. The weakness appears in two forms.
The first is omission. The framework exists, but a handler never invokes it, so the rules you wrote are never run. The second is incorrect use, such as declaring rules but not enabling the check on one route.
MITRE is careful to say this is not directly exploitable on its own. It leads to an exploitable condition only if proper validation is also missing later. There is a maintenance cost too. When developers skip the framework and validate by hand somewhere downstream, the next developer may not recognize that check and may remove or bypass it.
Here is a Spring style example. The first handler declares rules on the form class but never asks for them to be enforced.
// Vulnerable pattern: rules exist, but nothing enforces them
@PostMapping("/users")
public User create(@RequestBody UserForm form) {
return service.create(form);
}
// Fixed: @Valid triggers the framework check before the method body runs
@PostMapping("/users")
public User create(@Valid @RequestBody UserForm form) {
return service.create(form);
}
public class UserForm {
@NotBlank @Size(max = 64) private String name;
@Email private String email;
}
What an attacker gains
The record lists an integrity impact with an unexpected state. Unchecked input can lead to cross-site scripting, process control and SQL injection, among others. The framework gap is the door, and the injection flaw is what walks through it.
How to find it
MITRE lists automated static analysis. A static analysis tool can be told which application functions perform validation, and some know frameworks such as Struts already. It then lowers the priority of warnings on validated paths, so analysts can focus on code where validation appears to be missing.
The same record warns about false positives. Static analysis often cannot recognize validation it was not told about, so expect some noise.
Simple manual checks help:
- List every entry point that accepts external data and confirm each one invokes the framework.
- Look for handlers that parse raw request bodies or query strings directly.
- Search for hand written validation helpers that duplicate what the framework already does.
How to fix it
MITRE's mitigation is short: properly use the provided input validation frameworks. In practice that means three habits.
- Pick the framework your platform provides and make it the default path for every entry point.
- Declare rules close to the data type, and enforce them in one place, not scattered through handlers.
- Add a test that sends invalid input to each endpoint and expects rejection.
Try it yourself
Scan a small project for unvalidated entry points and see how a static scan reports them.
Click through it at your own pace, or open it full screen.
Quick check
Is skipping the validation framework directly exploitable?
Not by itself, according to MITRE. It becomes exploitable when proper validation is also missing later in the product, which can then allow injection style flaws.
Why do static analysis tools sometimes flag validated code?
They often cannot recognize validation they have not been told about, which produces false positives. Telling the tool which functions validate input reduces that noise.
