CVE-2026-64135 hwmon: (pmbus/adm1266) widen blackbox-info buffer to I2C_SMBUS_BLOCK_MAX
A stack buffer overflow in the Linux kernel adm1266 driver allows attackers with I2C access to cause memory corruption or 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-2026-64135?
CVE-2026-64135 is a medium-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) widen blackbox-info buffer to I2C_SMBUS_BLOCK_MAX
adm1266_nvmem_read_blackbox() declares a 5-byte stack buffer and passes it to i2c_smbus_read_block_data() to retrieve the 4-byte BLACKBOX_INFO response. i2c_smbus_read_block_data() does not honour caller buffer sizes -- it memcpy()s data.block[0] bytes from the SMBus transaction (where data.block[0] is the length byte returned by the slave device, up to I2C_SMBUS_BLOCK_MAX = 32):
memcpy(values, &data.block[1], data.block[0]);
If the device returns any block length above 5, the call overflows the caller's 5-byte stack buffer before the post-call
if (ret != 4) return -EIO;
check has a chance to reject the response.
Widen the local buffer to I2C_SMBUS_BLOCK_MAX so the helper has room for any well-formed SMBus block response, matching the convention used by the other i2c_smbus_read_block_data() callers in this driver.
Weakness: CWE-674
Which versions are affected by CVE-2026-64135?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64135?
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-2026-64135 being exploited?
There is no known exploitation of CVE-2026-64135 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64135, DEBIAN-CVE-2026-64135, GHSA-7g8h-gvx7-vxjc, UBUNTU-CVE-2026-64135.