Answer in brief
CVE-2026-64191 records a High severity (CVSS 7.8) vulnerability in i2c: stub: Reject I2C block transfers with invalid length. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=4710317891e4824ce1510a6b5066abbd3e917750 <7e9072dbd5f2f17934751873450d2c22080ead80 || >=4710317891e4824ce1510a6b5066abbd3e917750 <21e87f336ac6303fed54a69b1d0d79a23b25c8d0 || >=4710317891e4824ce1510a6b5066abbd3e917750 <3fd225f3e4cd67ec8ddab1afed9da03c7c43537c || >=4710317891e4824ce1510a6b5066abbd3e917750 <1c4ffe6b4f04365485ed58d64c9bb86b46fc9037 || >=4710317891e4824ce1510a6b5066abbd3e917750 <4bd8635f28c135a08aac6badcd7d9b5cdb34335f || >=4710317891e4824ce1510a6b5066abbd3e917750 <5f4d2bd028ebb6e4c09a9d64842546022321d4a7 || >=4710317891e4824ce1510a6b5066abbd3e917750 <0526931b16e5a118d367b7bfce7d797e63f7ac69 || >=4710317891e4824ce1510a6b5066abbd3e917750 <6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e | 7e9072dbd5f2f17934751873450d2c22080ead80, 21e87f336ac6303fed54a69b1d0d79a23b25c8d0, 3fd225f3e4cd67ec8ddab1afed9da03c7c43537c, 1c4ffe6b4f04365485ed58d64c9bb86b46fc9037, 4bd8635f28c135a08aac6badcd7d9b5cdb34335f, 5f4d2bd028ebb6e4c09a9d64842546022321d4a7, 0526931b16e5a118d367b7bfce7d797e63f7ac69, 6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e |
| Linux/Linuxgeneric | 2.6.33 | Not reported |
Published upstream
Jul 20, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 11, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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().
Quoted source text, attributed separately from HOL analysis.