{"affected":[{"database_specific":{"last_known_affected_version_range":"<= 4.2.0","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-67c9-f6v2-qv86/GHSA-67c9-f6v2-qv86.json"},"package":{"ecosystem":"NuGet","name":"Steeltoe.Discovery.Consul","purl":"pkg:nuget/Steeltoe.Discovery.Consul"},"ranges":[{"events":[{"introduced":"4.0.0"},{"fixed":"4.3.0"}],"type":"ECOSYSTEM"}],"versions":["4.0.0","4.1.0","4.2.0"]}],"aliases":["CVE-2026-81516"],"database_specific":{"cwe_ids":["CWE-755"],"github_reviewed":true,"github_reviewed_at":"2026-09-17T20:30:54Z","nvd_published_at":"2026-09-17T16:17:46Z","severity":"HIGH"},"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.","id":"GHSA-67c9-f6v2-qv86","modified":"2026-09-17T20:45:06.563253507Z","published":"2026-09-17T20:30:54Z","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"}],"schema_version":"1.9.0","severity":[{"score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","type":"CVSS_V3"}],"summary":"Steeltoe.Discovery.Consul: malformed 'secure' metadata aborts service instance lookup (DoS)"}