TL;DR
Researchers revealed Fabricked, a software-only attack that manipulates Infinity Fabric to compromise AMD SEV-SNP. The vulnerability allows malicious hypervisors to bypass memory protections, impacting AMD Zen processors.
Researchers have disclosed a new vulnerability, Fabricked, that exploits misconfigurations in AMD’s Infinity Fabric to compromise SEV-SNP, a hardware extension for confidential virtual machines. This flaw allows malicious hypervisors to bypass memory protections, risking data confidentiality for cloud tenants.
The Fabricked attack targets AMD Zen 3, Zen 4, and Zen 5 processors running SEV-SNP, a technology designed to create isolated, encrypted virtual machines that protect sensitive data from untrusted cloud providers. The attack hinges on manipulating the Infinity Fabric, a high-speed interconnect that links CPU cores, memory controllers, and the secure co-processor (PSP).
Specifically, the attack exploits the fact that the UEFI firmware, which is untrusted in this threat model, controls the configuration of the Infinity Fabric. By modifying the UEFI to skip certain configuration API calls, a malicious hypervisor can re-route memory transactions during system startup. This misconfiguration prevents the secure co-processor from properly initializing critical security structures, notably the RMP, which enforces memory access controls within CVMs.
As a result, the attacker can perform arbitrary read and write operations within the CVM’s memory space, effectively bypassing SEV-SNP protections. The vulnerability has been confirmed on AMD Zen 5 processors, with indications that Zen 3 and Zen 4 systems are also affected. AMD has issued firmware updates addressing the flaw.
Why It Matters
This vulnerability is significant because it undermines the core security guarantees of AMD’s SEV-SNP technology, widely used in confidential cloud computing. By enabling hypervisors to access VM memory directly, Fabricked threatens data privacy and integrity for cloud customers relying on AMD-based hardware. The fully deterministic, software-only nature of the attack means it can be executed without physical access, increasing its potential impact.
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Background
AMD SEV-SNP was introduced to enhance confidentiality in cloud environments by isolating virtual machines and encrypting their memory. The technology relies on the secure co-processor (PSP) to set up memory access controls during VM initialization. Prior to this disclosure, the security of SEV-SNP depended on the integrity of the platform firmware and correct configuration of the Infinity Fabric.
The vulnerability was discovered during research into the security assumptions of AMD’s hardware, revealing that the untrusted UEFI firmware controls the Infinity Fabric configuration. This oversight allows an attacker with hypervisor and UEFI privileges to reconfigure memory routing, effectively bypassing security measures designed to protect VM memory.
“Fabricked demonstrates that misconfiguring the Infinity Fabric can completely undermine AMD’s SEV-SNP protections, allowing arbitrary memory access within confidential VMs.”
— Research team at USENIX Security 2026
“We have released firmware updates to mitigate this vulnerability and recommend all affected systems be patched promptly.”
— AMD spokesperson
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What Remains Unclear
It is still unclear whether all AMD processors with SEV-SNP are vulnerable or if specific firmware versions mitigate the issue. Details about the attack’s applicability to different system configurations and potential hardware workarounds remain under investigation.
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What’s Next
AMD has issued firmware updates for affected processors, including Zen 3, Zen 4, and Zen 5. Researchers and security analysts will continue testing to confirm the scope of the vulnerability. Future updates may include hardware revisions or additional firmware patches to prevent similar attacks.
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Key Questions
Can this vulnerability be exploited remotely?
No. The attack requires hypervisor and UEFI privileges, meaning the attacker must already have significant control over the system to execute Fabricked.
Does this affect all AMD processors?
It affects Zen 3, Zen 4, and Zen 5 processors with SEV-SNP enabled, but the full scope depends on specific firmware configurations and updates.
What should users do to protect their systems?
Apply the latest firmware updates from AMD as soon as they are available and review system configurations to ensure proper security settings.
Is this a hardware or software vulnerability?
This vulnerability is primarily software-based, exploiting misconfigurations in firmware and system setup, but it impacts hardware security features.
