Executive brief
Steeltoe's Eureka discovery client is used by .NET applications to locate and connect to other services in a microservices architecture. A malformed field value in any service registration (such as an unrecognized action type or invalid timestamp) causes the entire registry to fail to deserialize, leaving all connected applications without access to the service registry and unable to discover dependent services until the bad registration is manually removed.
Technical details
The vulnerability is a deserialization failure in Steeltoe's Eureka discovery client that treats the entire registry response as a monolithic unit. When a service instance contains a field that fails to parse—such as an unrecognized `actionType` enum value, a non-boolean value for `isCoordinatingDiscoveryServer`, or a malformed timestamp—the entire deserialization operation aborts. This causes all Steeltoe clients connected to that registry to receive an empty or stale instance list, effectively disabling service discovery. The vulnerability requires write access to the Eureka registration API and is more likely to occur in mixed-platform environments where Java, Spring, or other non-.NET clients may register instances with unexpected field formats. A patch addressing this specific issue is available; as a mitigation, operators should audit the registry for non-standard field values and restrict write access to trusted services.
Affected products
- Steeltoe Discovery.Eureka unspecified
Timeline
- 2026-09-17: disclosed
- other: Related but distinct from CVE-2026-50196 addressing DataCenterInfo.name field