Spring Cloud Gateway CVE-2026-47879

Exploitation requires PR:H - the attacker must hold gateway administrative privileges sufficient to modify route configurations, typically via the Spring Cloud Gateway Actuator API (/actuator/gateway/routes) or direct access to the application's configuration files. The JsonToGrpcGatewayFilterFactory must be explicitly configured on at least one route; it is not active by default on all routes and the gateway must have been set up for JSON-to-gRPC transcoding. The vulnerable behavior is triggered when the gateway resolves the proto descriptor resource location specified in the filter configuration. Exploitation is additionally constrained by: (1) the gateway host must have network reachability to the targeted internal resource (the SSRF target must be accessible from the gateway's network position), and (2) environments using Spring Cloud Gateway's Actuator with proper authentication and role separation, or those not using the JsonToGrpcGatewayFilterFactory at all, are not practically exploitable. Deployments that expose the Actuator management port unauthenticated or with weak credentials face materially higher risk.

The vendor-supplied CVSS vector (AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N, score 8.7) accurately reflects the threat model: the PR:H metric is the key limiting factor, requiring gateway administrative credentials or write access to route configuration. This substantially narrows the exploitable population to insiders, compromised admin accounts, or environments with misconfigured access controls on the Gateway Actuator API. The scope-change (S:C) and C:H/I:H ratings are well-calibrated - SSRF through a cloud gateway can expose instance metadata, internal dashboards, or unauthenticated internal APIs. EPSS at 0.24% (15th percentile) and SSVC Exploitation: none are mutually consistent, reflecting no active exploitation observed. SSVC Technical Impact: total and Automatable: no also align - the impact ceiling is high, but the PR:H gate prevents automated mass scanning. No KEV listing or public POC exists. Real-world priority should be elevated for deployments using the JsonToGrpcGatewayFilterFactory filter specifically, and for environments where the gateway's network position gives it access to sensitive internal endpoints.

An attacker who has obtained Spring Cloud Gateway administrative credentials - via credential stuffing, a compromised CI/CD pipeline, or an exposed unsecured Actuator endpoint - modifies a route definition to apply JsonToGrpcGatewayFilterFactory with a proto descriptor URL pointing at an internal cloud metadata service (e.g., http://169.254.169.254/latest/meta-data/) or an unauthenticated internal management API. When the gateway processes a request matching that route, it fetches the attacker-specified URL from within the internal network, returning sensitive data to the attacker or triggering unintended state changes in backend systems. No public POC has been identified, but the attack technique is well-understood in SSRF literature.