Why API Gateway allows invalid dates

In AWS API Gateway, I have a model like this:

{
  "required" : [ "validUntil" ],
  "type" : "object",
  "properties" : {
    "validUntil" : {
      "$ref":"https://apigateway.amazonaws.com/restapis/xxxyyyzzz/models/Timestamp"
    },
    "deadline" : {
      "$ref":"https://apigateway.amazonaws.com/restapis/xxxyyyzzz/models/Date"
    }
  }
}

When I pass a request with invalid timestamp, e.g. 2023-12-32T00:00:00+00:00, i.e. December the 32nd, I get error as expected:

Gateway response body: {"errorCode":"BAD_REQUEST_BODY","message":"Invalid request body","description":"[format attribute \"date\" not supported, string \"2023-12-32T00:00:00+00:00\" is invalid against requested date format(s) [yyyy-MM-dd'T'HH:mm:ssZ, yyyy-MM-dd'T'HH:mm:ss.SSSZ]]"}

That works fine.

Yet... when I pass 2023-12-32 as deadline which uses Date model then the request is valid:

Request validation succeeded for content type application/json

Why is that? Why API Gateway doesn't trigger error?

Here are my models:

Date:

{
  "type" : "string",
  "description" : "Date in ISO 8601 format.",
  "format" : "date"
}

Timestamp

{
  "type" : "string",
  "description" : "Timestamp as defined by ISO 8601 with time offset.",
  "format" : "date-time"
}

JSON Schema specification: https://json-schema.org/understanding-json-schema/reference/string.html#dates-and-times

The section of the JSON Schema spec which you linked to states that the date type is new in draft 7, whereas the date-time type has been around for a longer time.

The AWS API gateway uses an old version of the JSON Schema spec, so it does not understand the date type.

From API Gateway documentation (in June 2023):
https://docs.aws.amazon.com/apigateway/latest/developerguide/models-mappings-models.html

> In API Gateway, models are defined using the JSON schema draft 4

Linked JSON Schema spec with date format is from draft 7

Thus, as API Gateway is using older specification, it doesn't validate date format as assumed.