In late March 2024, the open source community discovered a backdoor in XZ Utils, a suite of tools that use the xz compression algorithm. The xz backdoor was embedded inside liblzma, and took effect when liblzma was used in OpenSSH, a common remote-login tool. You can read about this extensively in many places elsewhere. Since then, many people leveraged the xz backdoor to highlight their favorite systemic issue in open source.