SARL: OO Framework Specification for Static Analysis -- QPR Verify: A Static Analysis Tool for Embedded Software based on Bounded Model Checking -- Verified Translation Between Purely Functional and Imperative Domain Specific Languages in HELIX -- Automatic Detection and Repair of Transition-Based Leakage in Software Binaries -- BanditFuzz: A Reinforcement-Learning based Performance Fuzzer for SMT Solvers -- Synthesis of Solar Photovoltaic Systems: Optimal Sizing Comparison -- Verfied Transformations and Hoare Logic: Beautiful Proofs for Ugly Assembly Language -- MCBAT: Model Counting for Constraints over Bounded Integer Arrays -- Optimized NTT Algorithm -- Can We Avoid Rounding-Error Estimation in HPC Codes and Still Get Trustworthy Results? -- An Efficient Floating-Point Bit-Blasting API for Verifying C Programs -- Rigorous Enclosure of Round-O Errors in Floating-Point Computations : Towards Numerical Assistants: Trust, Measurement, Community, and Generality for the Numerical Workbench -- Combining Zonotope Abstraction and Constraint Programming for Synthesizing Inductive Invariants -- SARL: OO Framework Speci cation for Static Analysis -- QPR Verify: A Static Analysis Tool for Embedded Software based on Bounded Model Checking -- Veri ed Translation Between Purely Functional and Imperative Domain Specific Languages in HELIX -- Automatic Detection and Repair of Transition-Based Leakage in Software Binaries -- BanditFuzz: A Reinforcement-Learning based Performance Fuzzer for SMT Solvers -- Synthesis of Solar Photovoltaic Systems: Optimal Sizing Comparison -- Veri ed Transformations and Hoare Logic: Beautiful Proofs for Ugly Assembly Language -- MCBAT: Model Counting for Constraints over Bounded Integer Arrays -- Verification of an Optimized NTT Algorithm -- Can We Avoid Rounding-Error Estimation in HPC Codes and Still Get Trustworthy Results? -- An Efficient Floating-Point Bit-Blasting API for Verifying C Programs -- Rigorous Enclosure of Round-O Errors in Floating-Point Computations -- Towards Numerical Assistants: Trust, Measurement, Community, and Generality for the Numerical Workbench -- Combining Zonotope Abstraction and Constraint Programming for Synthesizing Inductive Invariants.

This book constitutes the refereed proceedings of the 12th International Conference on Verified Software, VSTTE 2020, and the 13th International Workshop on Numerical Software Verification, NSV 2020, held in Los Angeles, CA, USA, in July 2020. Due to COVID-19 pandemic the conference was held virtually. The 13 papers presented in this volume were carefully reviewed and selected from 21 submissions. The papers describe large-scale verification efforts that involve collaboration, theory unification, tool integration, and formalized domain knowledge as well as novel experiments and case studies evaluating verification techniques and technologies. The conference was co-located with the 32nd International Conference on Computer-Aided Verification (CAV 2020).