CVE-2026-64086 hwmon: (pmbus/adm1266) include PEC byte in pmbus_block_xfer read buffer
A buffer overflow in the Linux kernel adm1266 PMBus driver allows attackers to write one byte past the end of a buffer, potentially leading to code execution or system crashes.
- 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-2026-64086?
CVE-2026-64086 is a high-severity memory corruption vulnerability in Linux kernel, published on 19 Jul 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:
hwmon: (pmbus/adm1266) include PEC byte in pmbus_block_xfer read buffer
adm1266_pmbus_block_xfer() sets up the read transaction with
.buf = data->read_buf, .len = ADM1266_PMBUS_BLOCK_MAX + 2,
but read_buf in struct adm1266_data is declared as
u8 read_buf[ADM1266_PMBUS_BLOCK_MAX + 1];
For a max-length block response (length byte = 255 + up to 1 PEC byte), the i2c controller is told to write 257 bytes into a 256-byte buffer, putting one byte past the end of read_buf. The same response also makes the subsequent PEC compare
if (crc != msgs[1].buf[msgs[1].buf[0] + 1])
read a byte beyond the array.
Bump the read_buf declaration to ADM1266_PMBUS_BLOCK_MAX + 2 so the buffer can hold the length byte, up to 255 payload bytes, and the PEC byte the i2c_msg length already accounts for.
Which versions are affected by CVE-2026-64086?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64086?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-64086 being exploited?
There is no known exploitation of CVE-2026-64086 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64086, DEBIAN-CVE-2026-64086, GHSA-f42m-8rh7-xp4f, UBUNTU-CVE-2026-64086.