Type-Coercion Fuzzers

These fuzzers send a value using a representation different from the OpenAPI schema, targeting frameworks that silently coerce request input. They are part of the type-coercion profile and are included in a full run.

The default expectation is 4XX, because strict validation should reject the wrong representation. Use --no-strictTypes when the API intentionally accepts the conversion and a 2XX response is valid.

Full Fuzzer Name	Log Key	Enabled by default?	Target field types	Expected result	Fuzzing logic	Conditions when skipped	HTTP methods skipped	Reporting
AlternativeDateTimeFormatsFieldsFuzzer	N/A	Yes in the type-coercion, coverage, crash, and full profiles	date-time fields	4XX by default; 2XX or 4XX with --no-strictTypes	Sends ISO local date (yyyy-MM-dd) and offset-less local date-time (yyyy-MM-dd'T'HH:mm:ss, yyyy-MM-dd HH:mm:ss) formats in date-time fields.	Empty payloads or requests without date-time fields.	HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
BooleanStringInBooleanFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	Boolean fields	4XX by default; 2XX with --no-strictTypes	Sends true and false as strings.	Non-boolean fields, enums, discriminators, and reference data.	GET, DELETE, HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
BooleanValuesInStringFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	String fields	4XX by default; 2XX with --no-strictTypes	Sends boolean values to string fields.	Non-string fields, enums, discriminators, and reference data.	GET, DELETE, HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
EnumNumericOrdinalFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	Enum fields	4XX by default; 2XX with --no-strictTypes	Sends the numeric ordinal of an enum value.	Non-enum fields, unsupported enum values, discriminators, and reference data.	HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
EpochNumberInDateTimeFieldsFuzzer	N/A	Yes in the type-coercion, crash, and full profiles	date-time fields	4XX by default; 2XX with --no-strictTypes	Sends an epoch number to a date-time field.	Fields without the date-time format, discriminators, and reference data.	HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
LeadingZerosInNumericFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	Numeric and integer fields	4XX by default; 2XX with --no-strictTypes	Sends valid numeric values encoded with leading zeros.	Non-numeric fields, values that cannot be represented with leading zeros, and reference data.	HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
NumericBooleansInBooleanFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	Boolean fields	4XX by default; 2XX with --no-strictTypes	Sends 0 and 1 as boolean representations.	Non-boolean fields, enums, discriminators, and reference data.	GET, DELETE, HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
NumericStringsInNumericFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	Numeric and integer fields	4XX by default; 2XX with --no-strictTypes	Sends numeric values encoded as strings.	Non-numeric fields, enums, discriminators, and reference data.	GET, DELETE, HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
NumericValuesInStringFieldsFuzzer	N/A	Yes in the type-coercion, quick, ci, coverage, crash, and full profiles	Request body string fields	4XX by default; 2XX with --no-strictTypes	Sends unquoted numeric values (including 64-bit integers) to string fields.	Non-string fields, URL path/query parameters, enums, discriminators, and reference data.	GET, DELETE, HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
ScientificNotationStringsInDecimalFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	Decimal and floating-point fields	4XX by default; 2XX with --no-strictTypes	Sends scientific-notation values encoded as strings.	Non-decimal fields, unsupported formats, and reference data.	HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
SingleElementArrayToScalarFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	Primitive fields	4XX by default; 2XX with --no-strictTypes	Wraps a valid primitive value in a single-element array.	Non-primitive fields, discriminators, and reference data.	GET, DELETE, HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
SmallNegativeAndInt32BoundaryFieldsFuzzer	N/A	Yes in the quick, ci, crash, and full profiles	Integer and numeric fields (including query parameters)	4XX when the value violates declared schema minimum/maximum bounds (with --strictTypes); 2XX or 4XX otherwise	Sends 0, -1, and Integer.MAX_VALUE (2147483647) to integer and numeric fields so values pass 32-bit deserialization and reach controller/service boundary checks.	Non-numeric fields, enums, discriminators, and reference data.	HEAD, TRACE	Follows normal CATS reporting against the expected response family.
SpecialFloatTokensInNumericFieldsFuzzer	N/A	Yes in the type-coercion, ci, crash, and full profiles	number and float/double fields	4XX by default; 2XX or 4XX with --no-strictTypes	Sends IEEE-754 special floating-point string tokens ("NaN", "Infinity", "-Infinity") to detect lenient float-parser coercion and downstream arithmetic or database crashes.	Non-number fields, enums, discriminators, and reference data.	HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.
WhitespacePaddedNumericFieldsFuzzer	N/A	Yes in the type-coercion and full profiles	Numeric and integer fields	4XX by default; 2XX with --no-strictTypes	Sends numeric values padded with whitespace.	Non-numeric fields, values that cannot be padded, and reference data.	HEAD, TRACE	Follows normal CATS reporting against the configured expected response family.

• AlternativeDateTimeFormatsFields sends ISO local date (yyyy-MM-dd) and offset-less local date-time (yyyy-MM-dd'T'HH:mm:ss and yyyy-MM-dd HH:mm:ss) strings to date-time fields.
• BooleanStringInBooleanFields sends true/false as strings to boolean fields.
• BooleanValuesInStringFields sends boolean values to string fields.
• EnumNumericOrdinalFields sends numeric enum ordinals to enum fields.
• EpochNumberInDateTimeFields sends epoch numbers to date-time fields.
• LeadingZerosInNumericFields sends numeric values with leading zeros.
• NumericBooleansInBooleanFields sends 0/1 representations to boolean fields.
• NumericStringsInNumericFields sends numeric values as strings.
• NumericValuesInStringFields sends numeric values to string fields.
• ScientificNotationStringsInDecimalFields sends scientific-notation values as strings to decimal fields.
• SingleElementArrayToScalarFields wraps primitive values in a single-element array.
• SmallNegativeAndInt32BoundaryFields sends 0, -1, and Integer.MAX_VALUE (2147483647) to integer and numeric fields.
• SpecialFloatTokensInNumericFields sends IEEE-754 "NaN", "Infinity", and "-Infinity" tokens to numeric fields.
• WhitespacePaddedNumericFields sends numeric values padded with whitespace.

List the profile and all exact registered names with:

cats list --profiles
cats list --fuzzers