Google Cloud Warns Three AMD Turin CPU Flaws Could Leak Data Across Processes in VMs - The Hacker News
Google Cloud has identified three AMD Turin CPU flaws that could allow data leakage across virtual machines, requiring patches and VM restarts.
Google Cloud has warned about three critical CPU vulnerabilities affecting its virtual machines running on AMD Turin processors. The flaws, classified as Transient Scheduler Attacks (TSA), could potentially allow attackers with code on the same processor core to infer data from other processes or the kernel within a virtual machine.
The affected machine series include C4D, N4D, H4D, Z4D, and G4, including bare-metal instances of C4D and Z4D. Turin is the code name for AMD's fifth-generation EPYC processors. Google has already applied mitigations for attacks between VMs and between VMs and the host system.
Vulnerability Details
Two of the flaws, TSA-SQ (CVE-2024-36350) and TSA-L1 (CVE-2024-36357), were first disclosed on July 8, 2025, for earlier EPYC processors. The third flaw, CVE-2026-0004, is new and may allow attackers to infer data in the processor's L1 data cache. AMD now states that its Zen 5 processors are impacted differently from previous AMD processors.
AMD had previously said that Zen5 CPUs were not vulnerable to TSA-SQ and TSA-L1.
Google rates the security issue as Medium severity, while AMD classifies all three flaws as local attacks with high attack complexity requiring only low privileges. As of now, none of the vulnerabilities are listed in the KEV catalog of exploited flaws maintained by the U.S. Cybersecurity and Infrastructure Security Agency, and neither company reports any active exploitation.
Customer Actions Required
Google Cloud customers running VMs on Turin processors must install their OS vendor's fix when available and then stop and start their VMs. The company emphasizes that "Rebooting the guest OS isn't enough." For bare metal instances of C4D and Z4D, customers must apply their own vendor fixes when available.
For Google Kubernetes Engine (GKE), updated node images for Turin-based bare metal instances will be made available, though they are not yet listed as available at the time of the bulletin. Cloud Run customers don't need to take any action. Customers on older Rome, Milan, and Genoa processors received similar instructions during the original disclosure in July 2025.
For Turin servers running on customer-owned hardware, AMD states that both platform firmware and OS updates are needed for full mitigation, which may affect performance. The Xen Project has published hypervisor patches, and microcode for all TSA flaws on Zen 5 has been in linux-firmware since September 23.
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