Unisys Libra 43xx, 63xx, and 83xx, and FS600 class systems with MCP-FIRMWARE 40.0 before 40.0IC4 Build 270 might allow remote authenticated users to cause a denial of service (data corruption or system crash) via vectors related to using program operators during EPSILON (level 5) based codefiles at peak memory usage, which triggers CPM stack corruption.