CVE-2026-55521Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs omits authorization checks in IndexesApi.listPacketIndex, IndexesApi.listEventIndex, Cop1Api.disable, Cop1Api.resume, Cop1Api.initialize, Cop1Api.updateConfig, and TimeApi.setTime. An authenticated low-privilege user can read packet and event index metadata without ObjectPrivilegeType.ReadPacket, alter COP-1 link state without SystemPrivilege.ControlLinks, and manipulate simulation time. These operations can disclose telemetry metadata, disrupt telecommand handling, and affect system integrity and availability. This issue is fixed in versions 5.12.8 and 5.13.2.