CVE-2026-9805 FMTSWriteUseIntelLib: FMTS SMM IHISI Buffer Overflow
A buffer overflow in the InsydeH2O BIOS SMM handler allows attackers to execute arbitrary code with high privileges.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-9805?
CVE-2026-9805 is a low-severity memory corruption vulnerability in InsydeH2O, published on 26 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
SMM IHISI command handler, FMTSWriteUseIntelLib, for FMTS command 0x32, read and write data without checking buffer size and could cause buffer overflow.
Weakness: CWE-787
Which versions are affected by CVE-2026-9805?
How do I fix CVE-2026-9805?
No fix has been published for CVE-2026-9805 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-9805 being exploited?
There is no known exploitation of CVE-2026-9805 in the wild and no public exploit code.
Sources
Also known as GHSA-q9cj-25hp-849c.