IOMMU Write Buffer Vulnerability
Summary
An internal security audit has found a potential vulnerability that may allow an attacker with privileges and a compromised hypervisor to write data outside the buffer length during host buffer access, potentially resulting in loss of SNP guest data integrity.
CVE Details
Refer to Glossary for explanation of terms
CVE |
CVE Description |
CVSS Score |
CVE-2023-20585 |
Insufficient checks of the RMP on host buffer access in IOMMU may allow an attacker with privileges and a compromised hypervisor to trigger an out of bounds condition without RMP checks, resulting in a potential loss of confidential guest integrity. |
5.3 (Medium) 5.6 (Medium) |
Affected Products and Mitigation
AMD recommends updating to the SEV firmware version indicated below.
Note: Mitigation of this vulnerability requires both a SEV firmware update and an OS-specific update. Mitigations may be deployed in any order, but both are required. Mitigation also requires SNP guest shutdown and reinitialization.
For mitigations requiring operating system (OS) updates, AMD recommends consulting with your operating system vendor’s documentation for information on how to enable the OS portion of the mitigation.
*Note: Products believed to not be affected by the listed CVEs may not be included.
AMD EPYC™ Series Processors
Please Note: OS updates will also be required to mitigate this vulnerability. Please refer to your OSV for additional information.
| Product | Former Codename | Mitigation3 Option 1: SEV FW + OS Option 2: AGESA + OS | SEV Mitigation Vector Bit2 | Release Date | TCB Values for SNP Attestation |
| AMD EPYC™ 7001 Series Processors | “Naples” | Not Affected | N/A | N/A | N/A |
| AMD EPYC™ 7002 Series Processors | “Rome” | Not Affected | N/A | N/A | N/A |
| AMD EPYC™ 7003 Series Processors | “Milan” “Milan-X” | Option 1: - SEV FW 1.37.23 + OS Update1 | 2 | 2025-07-03 | TCB[SNP]>=0x1B |
| Option 2: - Milan PI_1.0.0.H + OS Update1 | 2025-09-04 | ||||
| AMD EPYC™ 8004 Series Processors | “Siena” “Genoa” “Genoa-X” “Bergamo” | Option 1: - SEV FW 1.37.31 + OS Update1 | 2 | 2025-06-27 | TCB[SNP]>=0x1B |
| AMD EPYC™ 9004 Series Processors | Option 2: - GenoaPI_1.0.0.G + OS Update1 |
[1] For mitigations requiring Operating System (OS) updates, AMD recommends consulting with your Operating System vendor’s documentation for information on how to enable the OS portion of the mitigation.
[2] For more information please reference the SEV Secure Nested Paging Firmware ABI Specification (document 56860) available on https://www.amd.com/en/developer/sev.html
SEV Table
| CVE ID | SEV | SEV-ES | SEV-SNP |
| CVE-2023-20585 | N | N | Y |
AMD EPYC™ Embedded Series Processors
Please Note: OS updates will also be required to mitigate this vulnerability. Please refer to your OSV for additional information.
| Product | Mitigation | Release Date |
| AMD EPYC™ 7003 Embedded Series Processors | EmbMilanPI-SP3 1.0.0.B + OS Update | 2025-04-30 |
| AMD EPYC™ 9004 Embedded Series Processors | EmbGenoaPI-1.0.0.A + OS Update | 2025-05-02 |
Acknowledgement
CVE-2023-20585 was internally found
Revisions
| Revision Date | Description |
| 2026-04-14 | Initial publication |
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