CVE-2026-123807

Signal K Server: Unauthenticated path traversal in resources-provider v2 API leads to JWT secret disclosure, admin impersonation and remote code execution

Signal K Server is a server application that runs on a central hub in a boat. From 2.0.0 until 2.34.0 for Signal K Server and from 1.0.0 until 1.5.3 for @signalk/resources-provider, the v2 REST route GET /signalk/v2/api/resources/:resourceType/:resourceId accepts an unsafe resourceId that can escape the intended resource directory. The route passes the attacker-controlled resourceId through src/api/resources/index.ts to FileStore.getResource() in packages/resources-provider-plugin/src/filestorage.ts without adequate path containment, allowing arbitrary JSON files reachable by the server to be read. Related PUT and DELETE resource operations can write or delete files outside the storage root. Deployments with allow_readonly enabled permit anonymous reads, while other deployments require a readonly user token. Reading security.json exposes the HS256 JWT signing secret and password hashes, allowing an attacker to forge an administrator token. Administrative access to POST /skServer/providers can then create an Execute provider that runs commands with the server process privileges and persists its configuration across restarts. This issue is fixed in Signal K Server 2.34.0 and @signalk/resources-provider 1.5.3.