Reliability Risk Assessment Approaches in Software Engineering: A Review Structured by Software Development LifeCycle (SDLC) Phases and Reliable Sub-Characteristics

Reliability risk is a critical concern in software development, as failures can result in system downtime, degraded performance, data integrity issues, financial losses and loss of user trust. The increasing complexity of modern systems, driven by dynamic workloads, distributed architecture, and unpredictable interactions, amplifies these risks. In regulated industries like healthcare, finance, and transportation, software reliability directly affects safety, compliance and operational continuity, making robust risk assessment essential. Despite recent development and improvement on numerous reliability risk assessment techniques, system failures continue to be potent, creating concerns on scope, applicability and limitations. This paper will dive deep into evaluating recent methods, the advantages and disadvantages of the application itself, while critically assessing the research gaps. Here, the techniques are categorized across the software development lifecycle (SDLC), to bridge methods to phase-specific reliability needs. Consequently, the paper addresses methodological synthesis of recent practices, identifies segments where existing techniques fail to live up to expectations, and summarize future research directions for achieving more robust and adaptive reliability risk assessment.