GHSA-jpcw-4wr7-c3vq

| Field | Value | |---|---| | Ecosystem | Go | | Package | `github.com/getkin/kin-openapi` | | Affected versions | `<= 0.143.0` (introduced in `v0.2.0`, PR #90, 2019-05-07; reproduced on `HEAD` `30e2923`) | | Patched versions | 0.144.0 | --- ### Summary `openapi3filter.ValidateRequest` contains a NULL-pointer-dereference denial of service: any **unauthenticated** client can crash the request-validation path with a **single** HTTP request. When an operation declares a `content` parameter (as opposed to a `schema` parameter) whose media type object has **no `schema`**, request validation dereferences that missing schema and panics. The document is legal under the OpenAPI Specification — kin-openapi's own `doc.Validate()` accepts it — and the defect affects **both OpenAPI 3.0.x and 3.1.x**. Depending on how the library is wired into the server (see Impact), this ranges from a per-request abort with unbounded panic-log growth to a full remote process crash. ### Details The decoder used for `content` parameters when no custom `ParamDecoder` is configured (the library default), `defaultContentParameterDecoder`, dereferences the media-type schema without a nil check. `openapi3filter/req_resp_decoder.go`, around line 197: ```go mt := content.Get("application/json") if mt == nil { // media-type OBJECT is guarded ... err = fmt.Errorf("parameter %q has no content schema", param.Name) return } outSchema = mt.Schema.Value // ... but mt.Schema is NOT — panics when nil ``` The function guards `param.Content == nil`, `len(content) != 1`, and `mt == nil`, but never `mt.Schema == nil`. **Why a schema-less content parameter is legal** (so the sink is reachable — `doc.Validate()` returns no error), in both 3.0.x and 3.1.x: - `openapi3/parameter.go` — `Parameter.Validate` only enforces *exactly one of `schema` XOR `content`*; a parameter with `content` (and no `schema`) satisfies it. - `openapi3/media_type.go` — `MediaType.Validate` valida