Insyde H2O IHISI Command FMTSWriteUseIntelLib buffer overflow

Summaryinfo

A vulnerability classified as problematic has been found in Insyde H2O. Impacted is the function FMTSWriteUseIntelLib of the component IHISI Command Handler. This manipulation causes buffer overflow. This vulnerability appears as CVE-2026-9805. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability has been found in Insyde H2O (version now known) and classified as problematic. Affected by this vulnerability is the function FMTSWriteUseIntelLib of the component IHISI Command Handler. The manipulation with an unknown input leads to a buffer overflow vulnerability. The CWE definition for the vulnerability is CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. As an impact it is known to affect integrity, and availability. The summary by CVE is:

SMM IHISI command handler, FMTSWriteUseIntelLib, for FMTS command 0x32, read and write data without checking buffer size and could cause buffer overflow.

The advisory is shared at insyde.com. This vulnerability is known as CVE-2026-9805 since 05/28/2026. The exploitation appears to be easy. The attack can be launched remotely. Additional levels of successful authentication are necessary for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/26/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-66226). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Vendor

• Insyde

Name

• H2O

License

• commercial

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion