Single-use action or idempotency replay failure
A replay creates another protected effect where the operation must be unique or idempotent.
Candidate CWE: CWE-837
Test hypothesis#
Complete a one-time operation on a disposable object, then replay it once serially. For a documented idempotency key, compare same-key/same-body and same-key/changed-body behavior using sandbox data. For an integration event, separately replay one genuine signed delivery and inspect the worker effect after acknowledgement.
Evidence required#
A second unauthorized durable effect occurs, or the key crosses actor/tenant scope to affect another controlled object. Include the uniqueness contract and independent state count.
Rule out false positives#
Returning the original success response, safely reusing an existing result, or an intentionally repeatable action is not a replay vulnerability.
Playbook and command references#
- Workflow invariants, replay, idempotency, and races — Find security consequences in workflow ordering and concurrency, with serial controls and durable-state evidence.
- Webhooks and integration events: authenticity, tenant binding and replay — Verify the event signature, provider-to-tenant binding and durable worker effect together across retries and out-of-order delivery.
Find the associated command snippets
Referenced by these target playbooks#
Report checklist#
- Capture the affected version, configuration, identities, and object ownership.
- Preserve a valid baseline and a negative control.
- Reproduce the forbidden data access, action, or state change on controlled fixtures.
- Explain the intended security rule and why the observed behavior violates it.
- State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.
Conditional ATT&CK mapping#
No direct ATT&CK mapping selected. Record the weakness and demonstrated impact without forcing an adversary-behavior classification. See the mapping guide.