{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.177-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.95-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.0.14-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  i2c: stub: Reject I2C block transfers with invalid length  The I2C_SMBUS_I2C_BLOCK_DATA case in stub_xfer() uses data-\u003eblock[0] as the transfer length. The existing check only clamps it to avoid overrunning the chip-\u003ewords[256] register array, but does not validate it against I2C_SMBUS_BLOCK_MAX (32), which is the limit of the union i2c_smbus_data.block buffer (34 bytes total). The driver is a development/test tool (CONFIG_I2C_STUB=m, not built by default) that must be loaded with a chip_addr= parameter.  A local user with access to /dev/i2c-* can issue an I2C_SMBUS ioctl with I2C_SMBUS_I2C_BLOCK_DATA and data-\u003eblock[0] \u003e 32, causing stub_xfer() to read or write past the end of the union i2c_smbus_data.block buffer:   BUG: KASAN: stack-out-of-bounds in stub_xfer (drivers/i2c/i2c-stub.c:223)  Read of size 1 at addr ffff88800abcfd92 by task exploit/81  Call Trace:   \u003cTASK\u003e   stub_xfer (drivers/i2c/i2c-stub.c:223)   __i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:593)   i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:536)   i2cdev_ioctl_smbus (drivers/i2c/i2c-dev.c:391)   i2cdev_ioctl (drivers/i2c/i2c-dev.c:478)   __x64_sys_ioctl (fs/ioctl.c:583)   do_syscall_64 (arch/x86/entry/syscall_64.c:94)   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)   \u003c/TASK\u003e  The bug exists because i2c-stub implements .smbus_xfer directly, bypassing the I2C_SMBUS_BLOCK_MAX validation in i2c_smbus_xfer_emulated(). The I2C_SMBUS_BLOCK_DATA case in the same function correctly validates against I2C_SMBUS_BLOCK_MAX, but the I2C_SMBUS_I2C_BLOCK_DATA case does not.  Fix by rejecting transfers with data-\u003eblock[0] == 0 or data-\u003eblock[0] \u003e I2C_SMBUS_BLOCK_MAX with -EINVAL, consistent with both the I2C_SMBUS_BLOCK_DATA case in the same function and the I2C_SMBUS_I2C_BLOCK_DATA validation in i2c_smbus_xfer_emulated().",
  "id": "DEBIAN-CVE-2026-64191",
  "modified": "2026-09-14T16:47:37.671495930Z",
  "published": "2026-07-20T17:18:22.217Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64191"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-64191"
  ]
}