Experiencing traumatic events can lead to the development of posttraumatic stress disorder (PTSD) in susceptible individuals. Pinpointing risk factors and mechanisms that lower individual vulnerability to PTSD presents a significant clinical challenge with considerable promise in prevention and threapy. Here we aimed to identify pretrauma cognitive and emotional traits and their neurobiological correlates that predict posttrauma fear generalization, a core symptom of PTSD. An unbiased exploration of neurobehavioral vulnerability traits determining trauma-related fear generalization suggests prefrontal cortex-dependent cognitive functioning as a significant factor. We observed a strong association between lower pretrauma operant performance and excessive fear generalization, which could be partly reversed by posttrauma operant training leading to facilitated extinction. The degree of fear generalization (vulnerability) was reflected in prefrontal functions on multiple levels: altered gene expression profile related to interneurons (Crh, Vip) and plasticity in association with altered network activity. Particularly, CRH/VIP+ interneurons as major coordinators of network activity emerged as an important vulnerability factor for excessive fear generalization. Behavioral predictors showed gender differences. This set of data implies the potential use of prefrontal-dependent cognitive traits as neurobehavioral markers/predictors for fear generalization in PTSD. Such traits may be targeted in preventive measures and cognitive training interventions to alleviate these symptoms.