CVE-2026-114124: Electron: Off-screen rendering on macOS trusts GPU-supplied frame geometry

In offscreen rendering mode on macOS, frame data received from the GPU process was not fully validated by the main process. A compromised GPU process could cause the main process to read out-of-bounds memory while producing paint event images, disclosing memory or crashing the app. GHSA-pfmc-3mgc-p6fp covers the same issue on the other capture paths.

Apps are only affected if they use offscreen rendering (webPreferences.offscreen) on macOS and an attacker has separately gained code execution in the GPU process. Apps that do not use offscreen rendering are not affected.