Vulnerabilities in pkg:nuget/Steeltoe.Security.Authorization.Certificate

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5mq7-rwhj-4fh9",
  "modified" : "2026-09-17T20:30:58Z",
  "published" : "2026-09-17T20:30:58Z",
  "aliases" : [ "CVE-2026-81868" ],
  "summary" : "Steeltoe: Header-forwarded client cert lacks proof of private-key possession",
  "details" : "### Summary\n\nWhen Steeltoe's certificate-based authorization (`UseCertificateAuthorization`) is configured, the default configuration of the middleware relies on the `X-Client-Cert` HTTP header to identify the client certificate, without verifying private-key possession. This header is not stripped by common Cloud Foundry routers (like Gorouter or Envoy) on inbound requests.\n\n### Impact\n\nAn attacker who obtains the public certificate of an application instance in the target organization or space can spoof the `X-Client-Cert` header. This allows the attacker to bypass `SameOrg` and `SameSpace` authorization policies, granting unauthorized access to protected endpoints for the duration of the certificate's validity period.\n\n### Affected configuration\n\n- The application uses `AddOrgAndSpacePolicies()` and `UseCertificateAuthorization()` for inter-service authorization.\n- Inbound requests are not restricted to a known trusted proxy source IP.\n- The application's endpoints are network-accessible to the attacker (e.g., exposed to the internet via a public Cloud Foundry route, or the attacker has access to the internal Cloud Foundry network).\n\n### Mitigations\n\nIf an immediate upgrade to a patched version is not possible:\n\n- Restrict `UseCertificateForwarding` to trusted proxy source IPs using `ForwardedHeadersOptions.KnownProxies` and `KnownNetworks`.\n- Change the forwarding header to `X-Forwarded-Client-Cert` so that Cloud Foundry Gorouter and Envoy header stripping mechanisms apply to inbound untrusted requests.\n- Add a secondary authorization layer (e.g., a shared secret or mutual TLS at the proxy layer) for sensitive endpoints.\n- Ensure the application is not bound to a public route unless explicitly required. Use Cloud Foundry internal routes (e.g., `.apps.internal`) and container-to-container network policies to strictly limit network access to intended internal clients.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Steeltoe.Security.Authorization.Certificate"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.3.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.2.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-5mq7-rwhj-4fh9"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-81868"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/Steeltoe/commit/b626ef3d60aaf19c68eeeed5ee81045406c8c6d0"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/Steeltoe/releases/tag/4.3.0"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/SteeltoeOSS/security-advisories"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-288", "CWE-295" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-17T20:30:58Z",
    "nvd_published_at" : "2026-09-17T16:17:47Z"
  }
}