Fault Injection Attacks (FIAs) induce transient hardware faults to subvert software security mechanisms, yet assessing fault resilience, especially during early design phases, remains impractical without specialized laboratory equipment. Microarchitectural simulation provides a reproducible and scalable alternative. This paper presents InjectV, a gem5-based fault injection framework targeting RISC-V systems, which employs trace-guided fault injection by identifying Candidate Injection Points (CIPs) at security-critical operations including control-flow branches and conditional comparisons. Supporting transient corruption of architectural registers and physical memory under full-system simulation, InjectV demonstrates that guided fault injection requires 95.8% fewer injections than random exploration to expose successful attacks on the FISSC VerifyPIN benchmarks.