F´ (F Prime) is a framework that enables development and deployment of spaceflight and other embedded software applications. Prior to 4.2.0, Svc::FpySequencer STORE directive stack write validation the bounds check adds attacker-controlled offset and size before memcpy, allowing integer wraparound to make an out-of-range destination appear valid. When a sequence-controlled STORE directive supplies a stack offset and size whose U32 sum wraps, memcpy can write outside the sequencer stack, causing memory corruption, denial of service, and potentially code execution. This issue is fixed in version 4.2.0.