Missing Authorization

This is CWE-862: an endpoint or action performs no authorization check at all, as opposed to performing one incorrectly. It's a simpler, blunter version of the access-control problem than IDOR or incorrect authorization: there's no logic bug to find, because there's no logic there in the first place. Any authenticated user, regardless of role or ownership, can call the endpoint and have it succeed, because nobody ever asked whether they were allowed to. This often shows up on newer or less-visible endpoints, an admin action added quickly, an internal tool exposed through the same API surface as customer-facing features, where authentication (proving who you are) was implemented but authorization (checking what you're allowed to do) was assumed to follow automatically and never actually was.

• Admin or privileged actions added later in an application's life, alongside an existing, already-authenticated API surface
• Multi-tenant applications where an action correctly requires login but never checks whether the logged-in user belongs to the tenant being acted on
• Bulk or administrative operations (delete-all, export-all, user management) that assume only an admin would know the endpoint exists

• Authenticate as a low-privilege or ordinary user and directly call an endpoint that should require elevated privileges, checking whether it succeeds rather than returning a 403
• For multi-tenant actions, authenticate as a user belonging to one tenant and target a resource or action scoped to a different tenant, checking whether the tenant boundary is enforced at all

• No injected payload; the technique is calling a privileged or scoped endpoint directly with an ordinary authenticated session and observing whether it succeeds

For every discovered endpoint that appears privileged, administrative, or tenant-scoped based on its name or the data it touches, test it directly with an ordinary, low-privilege authenticated session rather than assuming the UI's own access restrictions reflect a real server-side check. A 200 response and a real state change or data return, rather than a 403, is the core signal, and it's often binary and unambiguous once found, unlike incorrect-authorization bugs which can require testing many role combinations to isolate.

Tip: Testing tools that run these checks in parallel across every discovered endpoint can cut the time required substantially compared to fully manual testing, as long as they confirm findings with more than one signal to keep the false-positive rate down.

Confirm the endpoint is genuinely meant to be restricted before treating a successful call as a finding; some endpoints are intentionally accessible to all authenticated users and only look privileged from their naming or URL structure.

Manual Testing Methodology

Here is a systematic approach to identifying Missing Authorization vulnerabilities in a target application.

Before testing, map all input vectors that could be affected. Identify parameters, headers, cookies, and request bodies that interact with the vulnerable component. A proxy such as Burp Suite or OWASP ZAP, paired with normal browsing of the target, is usually enough to build this list.

Send a legitimate request and record the normal response: status code, content length, response time, and any identifying tokens. This baseline matters because it's what you'll compare later responses against once payloads are involved.

Inject test payloads into each identified input vector one at a time. Start with benign detection payloads before escalating to anything that could actually trigger the vulnerability. For Missing Authorization specifically, authenticate as a low-privilege test account, then substitute identifiers belonging to another account (sequential IDs, UUIDs harvested from other responses) into every request, and separately try reaching privileged endpoints/actions directly by URL or method regardless of what the UI exposes to that role.

Compare the response against your baseline, looking specifically for a 200 response containing another user's data, or a privileged action completing successfully, when the authenticated user should have received a 401/403 — compare against the expected-denial baseline for that same request from the same account.

Once a potential vulnerability is detected, confirm it with at least a few independent test cases to rule out coincidence. Document the exact request and response as proof. For Missing Authorization, a confirmed finding typically means showing that attacker-controlled input changes the application's behavior in a way that matters for security, not just that a payload was reflected somewhere harmless.

Real-World Impact

Broken access control and IDOR let attackers access or modify resources belonging to other users simply by changing an identifier, or by reaching an endpoint that should have required a higher privilege level. It's one of the most commonly reported vulnerability classes precisely because the underlying mistake is conceptually simple, yet easy to overlook in authorization logic that only checks whether a user is logged in, not whether they're entitled to the specific resource or action being requested.

Real-world exploitation ranges from reading other users' private messages, files, or financial records, to modifying account settings, to reaching admin-only functionality by requesting it directly regardless of what the UI shows. In multi-tenant applications, it can mean cross-tenant data access entirely. The severity scales directly with how sensitive the exposed resource or action is.

This bug class shows up in virtually every kind of application, from social platforms to banking APIs to healthcare systems, which makes it one of the more consistently valuable checks to run regardless of what the target actually does — and one of the hardest for an automated scanner to catch reliably, since confirming it requires understanding what a specific user should and shouldn't be able to reach.

Prevention and Secure Coding

Preventing Missing Authorization takes a defense-in-depth approach — no single control below is sufficient alone, but together they close off both the primary path and the most common bypasses.

Object-level authorization on every request. Verify the authenticated user actually owns or is entitled to the specific resource identified in the request — on every endpoint that accepts an identifier, not just the ones that seemed sensitive during development.

Centralize the authorization logic. Implement authorization checks in one shared layer or middleware instead of re-implementing them per endpoint; re-implementation is exactly where individual endpoints get missed.

Default-deny. Require an explicit permission grant for each action a role can take, rather than granting broad access and trying to enumerate exceptions.

Indirect references where feasible. Opaque, per-user tokens in place of sequential database IDs make horizontal enumeration harder, though this is a hardening measure, not a substitute for the authorization check itself.

Test authorization from the attacker's seat, not the developer's. Authenticate as a low-privilege user and attempt every action a higher-privilege or different-tenant user could take — the UI hiding a button is not an authorization control.