CVE-2026-81516: Steeltoe.Discovery.Consul Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-67c9-f6v2-qv86",
  "modified" : "2026-09-17T20:30:54Z",
  "published" : "2026-09-17T20:30:54Z",
  "aliases" : [ "CVE-2026-81516" ],
  "summary" : "Steeltoe.Discovery.Consul: malformed 'secure' metadata aborts service instance lookup (DoS)",
  "details" : "## Summary\n\nSteeltoe's Consul discovery client parses the `secure` metadata field on each registered service instance using `bool.Parse`, which throws on any value other than `true` or `false`. A single service instance registered with a malformed `secure` value (for example `yes` or `1`) aborts construction of the entire instance list for that service, making the service undiscoverable. When `GetAllInstancesAsync` is used, one malformed instance in any service can abort enumeration across all services.\nThis is the same \"one malformed field aborts the whole batch\" availability class as [CVE-2026-50196](https://github.com/advisories/GHSA-j8ph-6fxj-g533), but affecting the Consul discovery client.\n\n## Impact\n\nAny principal that can register a service in the Consul catalog can trigger a service-discovery outage for all Steeltoe applications resolving that service. The outage affects all instances of the targeted service — not just the malformed one — and persists until the offending registration is removed.\n\n## Affected configuration\n\n- Application uses `ConsulDiscoveryClient` (any deployment).\n- The Consul catalog contains at least one service instance with a `secure` metadata value that is not `true` or `false`.\n- Mixed-platform environments where non-.NET clients register services with non-standard metadata values are more likely to encounter this condition.\n\n## Mitigations\n\nIf an immediate upgrade is not possible:\n\n- Audit the Consul catalog for service registrations with non-standard `secure` metadata values.\n- Restrict write access to the Consul service registration API to trusted services.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Steeltoe.Discovery.Consul"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "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-67c9-f6v2-qv86"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-81516"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/Steeltoe/commit/028569c4f4f0e9e393e3c22a4fa5d07987dd8673"
  }, {
    "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-755" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-17T20:30:54Z",
    "nvd_published_at" : "2026-09-17T16:17:46Z"
  }
}