Mior and Skyfall let rogue hosts read AMD SEV-SNP VM memory
Original title: New Mior and Skyfall Attacks Let Rogue Cloud Hosts Steal Secrets From AMD SEV-SNP VMs
Researchers forged attestation and recovered a test disk key; AMD rates the flaws 5.9 and 4.9 and points customers to server-maker updates.
ETH Zurich researchers published Mior, which needs a malicious hypervisor and BIOS to redirect SEV-SNP startup writes, then read or change a confidential VM and fake its attestation. ETH Zurich and Google's Skyfall uses Transient Scheduler Attacks after a failed VM start to recover saved registers, including a disk key in a modified test. AMD lists CVE-2026-0462 and CVE-2026-40671, with August 12 SEV firmware and later platform updates. No real-world exploitation is reported.
Unconfirmed: Mior was tested only on one Zen 5 chip; Zen 3 and Zen 4 were not tested. The IEEE committee questioned whether Skyfall's VM conditions are realistic.
- Mior succeeded in all 1,000 attempts on an EPYC 9135, including with ciphertext hiding.
- Skyfall was shown on EPYC 7313, 9124 and 9334, and not on Zen 5.
- Skyfall reads only three cache lines per page, at 0x0c0, 0x380 and 0x3c0.
- Platform firmware targets are November for Skyfall and December for Mior.
- Mior is separate from the earlier Fabricked and RMPocalypse RMP attacks.
Impact: Read confidential VM memory; Mior can also modify it and forge attestation.
| Product | Affected | Fixed in |
|---|---|---|
| AMD EPYC 7003 Milan SEV-SNP | — | SEV firmware 1.3A.03; platform firmware MilanPI-SP3_1.0.0.L |
| AMD EPYC 8004 SEV-SNP | — | SEV firmware 1.3A.4; platform firmware GenoaPI_1.0.0.K; Skyfall Genoa_100J Patch 3 |
| AMD EPYC 8005 Turin SEV-SNP | — | SEV firmware 1.3A.0A; platform firmware TurinPI_1.0.0.C |
| AMD EPYC 9004 SEV-SNP | — | SEV firmware 1.3A.4; platform firmware GenoaPI_1.0.0.K; Skyfall Genoa_100J Patch 3 |
- 1.Get the BIOS or platform firmware update from the server maker.
- Vendors
- AMD
- Organizations
- ETH ZurichGoogle
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-0462 | — | — | — | ||
| CVE-2026-40671 | — | — | — |
From the original article
6 min read at thehackernews.com
Two attacks made public this week allow a malicious host to read data inside AMD SEV-SNP-protected virtual machines (VMs), which are built to keep the server's operator out. One of them, Mior, can also modify a VM's memory and fake the signed report confirming which software it runs. Both need control of the server's hypervisor, and Mior also needs control of the server's BIOS.
thehackernews.com
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