SMM memory corruption via unchecked buffer size
Published Aug 26, 2026 · Updated Aug 26, 2026
Out-of-bounds writes in InsydeH2O UEFI BIOS allow physically proximate attackers to corrupt SMM memory through FMTS command 0x32. The FMTSWriteUseIntelLib SMM IHISI handler reads and writes command data without validating the supplied buffer size, allowing access beyond the intended buffer. Reaching the handler requires physical access, high privileges, user interaction, and platform-specific x86 firmware; exploitation can corrupt SMM state or interrupt firmware operation.
Summary
What happened
Out-of-bounds writes in InsydeH2O UEFI BIOS allow physically proximate attackers to corrupt SMM memory through FMTS command 0x32. The FMTSWriteUseIntelLib SMM IHISI handler reads and writes command data without validating the supplied buffer size, allowing access beyond the intended buffer. Reaching the handler requires physical access, high privileges, user interaction, and platform-specific x86 firmware; exploitation can corrupt SMM state or interrupt firmware operation.
The record
- CVE
- CVE-2026-9805
- Published
- Aug 26, 2026
- Updated
- Aug 26, 2026
- Vendor
- Insyde Software
- Product
- InsydeH2O UEFI BIOS
- Classifications
- CWE-787
- Attack vector
- physical
- Privileges
- admin
Timeline
How it unfolded
- Aug 26, 2026CVE publishedPublication date reported by the CVE source.
- Aug 26, 2026Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
Published CVSS scores
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Attacks
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Technologies
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