Medium · published October 16, 2026
libIEC61850 is an open-source implementation of IEC 61850 client and server protocols including MMS, GOOSE, Sampled Values, and R-Session. From 1.6.1 until 1.6.2, a successful MMS ObtainFile operation closes MmsObtainFileTask::fileHandle but leaves the stale non-NULL value in a task marked MMS_FILE_UPLOAD_STATE_NOT_USED. If a later ObtainFile request reuses that task and destination creation fails, MMS_FILE_UPLOAD_STATE_SEND_OBTAIN_FILE_ERROR_DESTINATION cleanup closes the stale FILE object again. Servers with the MMS file service and ObtainFile enabled can therefore be crashed remotely by the success-then-failure request sequence. This issue is fixed in version 1.6.2.