April 20, 2026For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above. Leidos Digital Modernization sector is seeking an experienced Senior Information System Security Engineer to support the delivery, enhancement, and adoption of enterprise data and analytics products used across multiple DoD organizations.