IOMMU Improper Exception Handling and SMM Out-of-Bounds Write Vulnerabilities
Summary
A denial-of-service vulnerability exists in the IOMMU invalidation handling logic where invalidation requests may be sent to PCIe devices that do not support Address Translation Cache (ATC). An attacker controlling a guest VM could trigger a condition that causes the IOMMU to wait indefinitely for a completion response, resulting in denial of service impacting the hypervisor and/or other guests.
An out-of-bounds write vulnerability exists in AmdMmSaveStateLib that may result in corruption of adjacent SMM memory. Successful exploitation could lead to SMM instability or denial of service on affected platform configurations.
CVE Details
Refer to Glossary for explanation of terms
CVE |
CVE Description |
CVSS Score |
CVE-2026-14968 |
An out-of-bounds write in TianoCore EDK II’s UefiCpuPkg MmSaveStateReadRegisterByIndex (AmdMmSaveState.c) allows a local attacker with SMM privileges on AMD platforms where NeedSysCall() returns TRUE to corrupt SMRAM. The flaw stems from improper handling of save-state register widths, leading to unintended 4-byte writes that can compromise SMM handler integrity and system availability. |
7.0 CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H 787 - Out-of-bounds Write
|
CVE-2024-21954 |
Improper exception handling in IOMMU could allow an invalidate command to be sent to PCIe devices that do not support Address Translation Cache (ATC), potentially resulting in denial of service. |
7.0 CWE-754: Improper Check for Unusual or Exceptional Conditions |
Specific CVSS scores may change subject to your implementation. We encourage you to calculate CVSS scores independently for your system.
Affected Products and Mitigation
AMD recommends updating to the Platform Initialization (PI) firmware version indicated below (note the PI firmware versions were released by AMD to the Original Equipment Manufacturers (OEM) on the dates listed below). Please contact your OEM for the BIOS update specific to your product(s).
*Note: Products believed to not be affected by the listed CVEs are not included.
AMD EPYC™ Series Processors
Product |
CVE ID |
Mitigation |
Mitigation Release Date |
AMD EPYC™ 4004 Series Processors |
CVE-2026-14968 (non-AMD) |
ComboAM5PI_1.2.0.3l (when utilizing SMM Supervisor); EDKII Patch (when not utilizing SMM Supervisor) |
2026-08-19 |
AMD EPYC™ 4005 Series Processors |
CVE-2026-14968 (non-AMD) |
ComboAM5PI_1.2.0.3l (when utilizing SMM Supervisor); EDKII Patch (when not utilizing SMM Supervisor) |
2026-08-19 |
AMD EPYC™ 7003 Series Processors |
CVE-2024-21954 |
MilanPI-SP3_1.0.0.J |
2025-12-02 |
AMD EPYC™ 9004 Series Processors |
CVE-2024-21954 |
GenoaPI_1.0.0.H |
2025-12-15 |
AMD EPYC™ Embedded Series Processors
Product |
CVE ID |
Mitigation |
Mitigation Release Date |
AMD EPYC™ Embedded 2005 Series Processors |
CVE-2026-14968 (non-AMD) |
EmbeddedFireRangeFL1_1.0.0.5 |
2026-08-30 |
AMD EPYC™ Embedded 4005 Series Processors |
CVE-2026-14968 (non-AMD) |
EmbeddedAM5PI_1.0.0.9 |
2026-09-28 |
AMD EPYC™ Embedded 7003 Series Processors |
CVE-2024-21954 |
EmbMilanPI-SP3 1.0.0.D |
2026-01-02 |
AMD EPYC™ Embedded 9004 Series Processors (formerly codenamed "Genoa") |
CVE-2024-21954 |
EmbGenoaPI-SP5 1.0.0.D |
2026-02-02 |
Acknowledgement
Internally reported
Revisions
| Revision Date | Description |
| 2026-11-10 | Initial version |
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