CVE-2026-45865 mctp i2c: initialise event handler read bytes
An attacker can read uninitialized stack memory via MCTP I2C events, potentially exposing sensitive kernel data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45865?
CVE-2026-45865 is a medium-severity vulnerability in Linux kernel, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mctp i2c: initialise event handler read bytes
Set a 0xff value for i2c reads of an mctp-i2c device. Otherwise reads will return "val" from the i2c bus driver. For i2c-aspeed and i2c-npcm7xx that is a stack uninitialised u8.
Tested with "i2ctransfer -y 1 r10@0x34" where 0x34 is a mctp-i2c instance, now it returns all 0xff.
Which versions are affected by CVE-2026-45865?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-45865?
Apply the vendor's patch.
Is CVE-2026-45865 being exploited?
There is no known exploitation of CVE-2026-45865 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-45865, DEBIAN-CVE-2026-45865, GHSA-6j35-qr59-823q, ROOT-OS-UBUNTU-2404-CVE-2026-45865, UBUNTU-CVE-2026-45865.