The vulnerability manifests in optimization passes handling type checks and memory operations. Key issues were identified in: 1) BackwardPass.cpp's failure to restrict type check elimination for stores (risk of aux slot miscalculations), 2) GlobOptFields.cpp's type mismatch handling during property specialization (incorrect type assumptions), and 3) Lower.cpp's type check validation gaps for destination operands (missing write validation). These were directly addressed in security patches through boundary checks and condition tightening, indicating they were root causes of the OOB write vulnerability.