CVE-2026-70598: Electron: Off-screen rendering trusts GPU-supplied geometry over shared-memory size

In offscreen rendering mode, 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.

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