A new technical paper titled “Memory DisOrder: Memory Re-orderings as a Timerless Side-channel” was published by researchers at University of Washington, Duke University, UC Santa Cruz, Raytheon and Microsoft Research.

Abstract

“To improve efficiency, nearly all parallel processing units (CPUs and GPUs) implement relaxed memory models in which memory operations may be re-ordered, i.e., executed out-of-order. Prior testing work in this area found that memory re-orderings are observed more frequently when other cores are active, e.g., stressing the memory system, which likely triggers aggressive hardware optimizations. In this work, we present Memory DisOrder: a timerless side-channel that uses memory re-orderings to infer activity on other processes. We first perform a fuzzing campaign and show that many mainstream processors (X86/Arm/Apple CPUs, NVIDIA/AMD/Apple GPUs) are susceptible to cross-process signals. We then show how the vulnerability can be used to implement classic attacks, including a covert channel, achieving up to 16 bits/second with 95% accuracy on an Apple M3 GPU, and application fingerprinting, achieving reliable closed-world DNN architecture fingerprinting on several CPUs and an Apple M3 GPU. Finally, we explore how low-level system details can be exploited to increase re-orderings, showing the potential for a covert channel to achieve nearly 30K bits/second on X86 CPUs. More precise attacks can likely be developed as the vulnerability becomes better understood.”

Find the technical paper here. January 2026.

Siddens, Sean, Sanya Srivastava, Reese Levine, Josiah Dykstra, and Tyler Sorensen. “Memory DisOrder: Memory Re-orderings as a Timerless Side-channel.” arXiv preprint arXiv:2601.08770 (2026).