CVE-2026-100353: kin-openapi: Incomplete Fix for GHSA-p6wj-qrr4-pgh5: Three Unpatched nil-Items Panic Paths in openapi3filter

The fix for GHSA-p6wj-qrr4-pgh5 addressed a nil-pointer dereference that occurs when an OpenAPI 3.1 array schema omits the items keyword (which is legal under JSON Schema 2020-12). That fix patched three decoder paths: the standalone parseArray function, the top-level array check in UrlencodedBodyDecoder, and MultipartBodyDecoder.

Three additional crash paths were missed. All of them reach the unguarded urlValuesDecoder.parseArray method (openapi3filter/req_resp_decoder.go:576) or the unguarded array branch in buildResObj (line 1015):

1. Query parameters with type: array and no items.
2. deepObject query parameters containing an array property with no items.
3. URL-encoded request bodies where the array lives inside an allOf / anyOf / oneOf sub-schema. This path bypasses the guard added by the GHSA-p6wj-qrr4-pgh5 fix, because that guard only inspects top-level properties.

Each path is triggerable by an unauthenticated client and produces a deterministic nil-pointer panic during request validation.