While going through a dataset of 1.4M+ API test executions, one pattern stood out pretty quickly:
- Most teams are doing a decent job testing authentication, but they’re consistently skipping authorization edge cases.
- And that gap isn’t theoretical. It shows up directly in production failures.
What the Data Actually Suggests
Across all these test runs, 34% of failures had a direct security implication. That’s not a small slice; it’s a third of everything breaking.
A large chunk of those failures was tied to authentication and authorization. But interestingly, it’s not because authentication systems are poorly implemented. The issue is more subtle: the right scenarios simply aren’t being tested.
There’s a clear pattern here:
- Teams validate that a token exists and works,
- but rarely verify what that token is actually allowed to do.
Where Things Usually Break
If you look closely, the same kinds of issues keep repeating:
- A token with limited permissions can access an endpoint it shouldn’t.
- An expired token continues to work because only the signature is checked.
- A user logs out, but their token remains valid because the system is stateless.
None of these are particularly complex bugs. They’re the result of incomplete validation — and more importantly, incomplete test coverage.
The Classic Example Most APIs Miss
Take a simple endpoint that fetches a resource by ID. Authentication is in place, tokens are validated, and everything seems correct.
But if the system never verifies that the resource actually belongs to the requesting user, you end up with a Broken Object Level Authorization (BOLA) issue.
All it takes is swapping an ID in the request. If the API still returns data, you’ve got a serious problem.
What’s surprising is not how this happens, but how rarely it’s tested.
New Code Is Where the Risk Is Highest
Another pattern that stood out was how frequently issues appear in newly added endpoints.
Endpoints in their first few weeks tend to have significantly higher failure rates. It’s easy to see why: new routes are often added quickly,
They might be wired slightly differently, and they’re not always covered by the same middleware or test scenarios as older endpoints.
Functional tests pass, everything looks fine, and the gaps only show up later.
What You Can Do About It
The fix here isn’t complicated, and it doesn’t require new tools:
The fix here isn’t complicated, and it doesn’t require new tools.
It starts with expanding how you think about test coverage.
Instead of only verifying that requests succeed or fail, you need to test why they succeed or fail.
That means deliberately checking edge cases:
- What happens when a valid token doesn’t have the right permissions?
- What happens when a token has expired?
- What happens when one user tries to access another user’s data?
These are simple scenarios, but they force your system to prove that authorization logic is working correctly.
Another often overlooked area is how your API interacts with external services. If your application consumes third-party APIs and passes that data downstream, validating the structure of those responses becomes important. Without that, unexpected or malformed data can quietly propagate through your system.
Why This Matters More Than It Seems
What stands out is that most of these issues aren’t caused by complex vulnerabilities or sophisticated attacks.
They exist because certain assumptions go untested.
Teams assume:
- If authentication works, authorization probably does too
- If a route is protected elsewhere, new ones will be too
- If a token is valid, it should be accepted
And those assumptions are exactly where things break.
Final Thought
Teams performing better aren’t necessarily using advanced techniques; they simply ensure these checks exist and run continuously within their pipelines because most issues aren’t hidden—they’re just untested.
Check out the full State of Security Testing here.
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