CVE-2026-64191

CVE CVE-2026-64191EUVD EUVD-2026-46011Published 2026-07-20T16:27:51.000ZLast changed 2026-08-05T12:39:59.000ZCVSS 7.8

What the advisory describes

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->block[0] as the transfer length. The existing check only clamps it to avoid overrunning the chip->words[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->block[0] > 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: <TASK> 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) </TASK> 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->block[0] == 0 or data->block[0] > 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().

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux patch: 5.10.260; patch: 7.0.14; 4710317891e4824ce1510a6b5066abbd3e917750 <21e87f336ac6303fed54a69b1d0d79a23b25c8d0; 4710317891e4824ce1510a6b5066abbd3e917750 <4bd8635f28c135a08aac6badcd7d9b5cdb34335f; patch: 5.15.211; patch: 6.18.37; patch: 6.6.144; 4710317891e4824ce1510a6b5066abbd3e917750 <5f4d2bd028ebb6e4c09a9d64842546022321d4a7; 4710317891e4824ce1510a6b5066abbd3e917750 <7e9072dbd5f2f17934751873450d2c22080ead80; 2.6.33; 4710317891e4824ce1510a6b5066abbd3e917750 <6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e; 4710317891e4824ce1510a6b5066abbd3e917750 <0526931b16e5a118d367b7bfce7d797e63f7ac69; patch: 0; patch: 6.1.177; patch: 6.12.95; patch: 7.1; 4710317891e4824ce1510a6b5066abbd3e917750 <1c4ffe6b4f04365485ed58d64c9bb86b46fc9037; 4710317891e4824ce1510a6b5066abbd3e917750 <3fd225f3e4cd67ec8ddab1afed9da03c7c43537c

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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