In this AWS re:Inforce 2023 session, Mark Ryland and David Nalley discuss AWS's commitment to open source software (OSS) security. They explore AWS's contributions to critical security technologies like AWS libcrypto, s2n, post-quantum crypto, Amazon Corretto, Firecracker, and Bottlerocket. The speakers also highlight AWS's efforts to enhance the security of the upstream OSS supply chain through collaborations with the Open Source Security Foundation (OpenSSF). This session provides valuable insights into AWS's ongoing work to improve open source security and its impact on the broader cloud ecosystem.