kb5124880

KB5124880 is a Microsoft-delivered Phi Silica AI component update for Intel-powered Copilot+ PCs running Windows 11 24H2 and 25H2. This August 2026 package, version 1.2608.951.0, replaces KB5121638 and appears in Windows Update history as an AI-model component update, not a Windows cumulative update. It contains no published bug-fix list, model-size figure, or performance claims. For administrators and developers, the practical change is version movement on a locally installed language model. The update is delivered automatically to eligible systems, and its scope is narrowly defined as an AI component update, making it relevant for those tracking Windows 11 updates on Copilot+ hardware.