TL;DR: Broken object authorization, broken authentication, and IDOR can let valid-looking API requests reach data or functions they should never touch, StackHawk explains. APIs then need object-level checks, authenticated request validation, and throttling to keep abuse from looking like normal use.
Editorial analysis by NHI Mgmt Group, based on content published by StackHawk: “Developer’s Guide to Fixing The 6 Most Common API Vulnerabilities”.
Key questions
Q: Why do broken API authentication controls create such a large breach risk?
A: Broken API authentication is dangerous because a valid caller can be accepted before any deeper control has a chance to stop abuse.
Q: What are the signs that an API is being probed for abuse?
A: Common signs include repeated tweaks to user IDs or object IDs, a growing number of errors from the same entity, and requests that test privilege escalation or access boundaries.
Q: What breaks when API authorization only checks the logged-in user, not the object being accessed?
A: Broken object-level authorization creates a gap where an authenticated caller can still reach records, properties, or functions it should never see.
Practitioner guidance
- Enforce object-level authorization on every API request Verify the caller’s entitlement against the specific object or record being requested, not just the endpoint or session.
- Harden API authentication lifecycles Set explicit expiry, rotation, and revocation rules for API keys, tokens, and service credentials, then validate them at each call.
- Throttle abusive request patterns Apply rate limits and anomaly thresholds to sensitive endpoints, especially login, lookup, export, and search functions.
Bottom line: API vulnerabilities are often access-control failures in disguise, which is why they sit at the intersection of AppSec, IAM, and NHI governance.
Glossary terms: Broken Object-Level Authorization, Broken Authentication, Rate Limiting, Insecure Direct Object Reference
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API security is now an identity control problem, not just an application bug problem. The article’s six vulnerability classes all reduce to the same governance issue: who or what is allowed to access which object, function, or data set through an API. That matters because APIs increasingly carry both human and non-human access, so IAM and NHI teams must treat authorization as a runtime enforcement problem rather than a login event. Practitioners should align API control design with identity governance, not leave it isolated inside AppSec.
A few things that frame the scale:
- Secrets management is a top five cybersecurity priority for only 33% of organisations, behind cloud security (45%), API security (42%), and endpoint security (36%), according to the 2024 State of Secrets Management Survey.
A question worth separating out:
Q: When should organisations prioritise rate limiting over request validation for API protection?
A: Prioritise rate limiting when the immediate problem is request volume, abuse, or repeated calls that can exhaust capacity or distort service behaviour. Use request validation when the main risk is malformed input, schema violations, or unexpected payloads reaching the application. In mature environments, both controls are complementary: one protects availability, the other protects request integrity.
👉 Read our full editorial: API vulnerabilities expose object access, auth, and data controls