Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to versions 42.11.6, 43.7.3, 44.4.3, and 45.0.0-alpha.9, frame data received from the GPU process for macOS offscreen rendering was not fully validated by the main process. An attacker who had separately gained code execution in the GPU process could provide inconsistent frame geometry and cause the main process to read out-of-bounds memory while producing paint event images, disclosing memory or crashing the application. This issue is fixed in versions 42.11.6, 43.7.3, 44.4.3, and 45.