arXiv:2603.17880v2 Announce Type: replace Abstract: The Open Radio Access Network Alliance (O-RAN) architecture enables third-party applications to optimize Radio Access Networks (RANs) at multiple timescales. However, the real-time distributed applications (known as dApps) that demand low latency, high performance, and resource isolation remain underexplored. Existing approaches propose collocating a new RAN Intelligent Controller (RIC) at the edge, or deploying dApps in bare metal along with RAN functions. The former approach increases network complexity and requires additional edge computing resources, and the latter raises serious security concerns due to the lack of native mechanisms to isolate dApps and RAN functions. Meanwhile, WebAssembly (Wasm) has emerged as a fast, lightweight technology for robust execution of external, untrusted code. In this work, we propose a new approach to executing dApps using Wasm to isolate applications in real-time in O-RAN. Results from a proof-of-concept implementation show that our lightweight and robust approach can provide predictable, deterministic performance, resource isolation, and low latency, supporting real-time control loops.