kin-openapi: Nil-pointer dereference panic in openapi3filter for OpenAPI 3.1 array schemas missing items

{
  "id": "6049855544fcffa7949ebdfb7c83c9c84b05663f783604831852ee7e2caad76d",
  "url": "https://osv.dev/vulnerability/GHSA-p6wj-qrr4-pgh5",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "kin-openapi: Nil-pointer dereference panic in openapi3filter for OpenAPI 3.1 array schemas missing items",
    "summary": "### Summary A nil-pointer dereference in `openapi3filter` lets any unauthenticated client crash a request handler with a single HTTP request against an OpenAPI **3.1** operation that declares `type: array` **without** `items`. OpenAPI 3.1 (JSON Schema 2020-12) permits omitting `items`, and `doc.Validate()` accepts such schemas with `Schema.Items == nil`. Request/response decoders then dereference `Items` with no nil check. The panic is **deterministic (100%)** on every request to the affected operation. There is no `recover()` in `openapi3filter`; under handlers without per-request recover the process can exit. ### Details **Spec-validation asymmetry.** OpenAPI 3.0 rejects array schemas that omit `items` ([`openapi3/schema.go`](https://github.com/getkin/kin-openapi/blob/master/openapi3/schema.go) around the `TypeArray` / `newSchemaItemsRequired` branch). For OpenAPI 3.1, `T.Validate` enables `jsonSchema2020ValidationEnabled`, so that check is skipped and `Schema.Items` remains nil after a clean `doc.Validate()`. **Vulnerable decoder.** The primary request-side crash is in [`UrlencodedBodyDecoder`](https://github.com/getkin/kin-openapi/blob/master/openapi3filter/req_resp_decoder.go) (still present on this checkout at L1421): ```go case propType.Is(\"array\"): items := propSchema.Value.Items.Value // Items == nil → panic ``` This runs during schema inspection **before** form values are parsed. Any non-empty `application/x-www-form-urlencoded` body for the operation reaches the de",
    "evidence": "osv:GHSA-p6wj-qrr4-pgh5",
    "products": [
      {
        "name": {
          "value": "github.com/getkin/kin-openapi",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.143.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-p6wj-qrr4-pgh5",
      "aliases": [
        "CVE-2026-97394",
        "GHSA-p6wj-qrr4-pgh5"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.136.0"
                },
                {
                  "fixed": "0.143.0"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/getkin/kin-openapi",
            "purl": "pkg:golang/github.com/getkin/kin-openapi",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-p6wj-qrr4-pgh5/GHSA-p6wj-qrr4-pgh5.json"
          }
        }
      ],
      "modified": "2026-10-21T03:11:56.394072112Z",
      "provider": "osv",
      "references": [
        "https://github.com/getkin/kin-openapi/security/advisories/GHSA-p6wj-qrr4-pgh5",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-97394",
        "https://github.com/getkin/kin-openapi/commit/30e292371a89ca6d1f91a9553e0aa518b49f838d",
        "https://github.com/getkin/kin-openapi",
        "https://github.com/getkin/kin-openapi/releases/tag/v0.143.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-248",
          "CWE-476"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-15T16:18:25Z",
        "github_reviewed_at": "2026-10-15T20:14:54Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-97394",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 391583,
  "published_at": "2026-10-15T20:14:54+00:00"
}