| Full Fuzzer Name | UnderflowArraySizeFieldsFuzzer |
| Log Key | UASFF |
| Description | Sends JSON arrays with fewer elements than the OpenAPI minItems constraint (minItems - 1) to verify minimum array size validation. |
| Enabled by default? | Yes (included in ci, crash, and full profiles) |
| Target field types | Array fields declaring minItems > 0 |
| Expected result when fuzzed field is required | 4XX |
| Expected result when fuzzed field is optional | 4XX |
| Expected result when fuzzed value is not matching field pattern | 4XX |
| Fuzzing logic | Replaces each array field that declares minItems > 0 with an array of size minItems - 1 ([] when minItems == 1). |
| Conditions when this fuzzer will be skipped | When a field is not a JSON array or does not declare minItems > 0. |
| HTTP methods that will be skipped | None |
| Reporting | Reports error if the server accepts the underflow array with 2XX or fails with 5XX; reports success when rejected with 4XX. |