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Review reviewHigh

CVE-2026-64191

Linux

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 ac...

CVSS
7.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.21
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.8

Vulnerability overview

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 ac...

Affected product and versions

Product
Linux
Affected versions
>= 4710317891e4824ce1510a6b5066abbd3e917750 < 7e9072dbd5f2f17934751873450d2c22080ead80, >= 4710317891e4824ce1510a6b5066abbd3e917750 < 21e87f336ac6303fed54a69b1d0d79a23b25c8d0, >= 4710317891e4824ce1510a6b5066abbd3e917750 < 3fd225f3e4cd67ec8ddab1afed9da03c7c43537c, >= 4710317891e4824ce1510a6b5066abbd3e917750 < 1c4ffe6b4f04365485ed58d64c9bb86b46fc9037, >= 4710317891e4824ce1510a6b5066abbd3e917750 < 4bd8635f28c135a08aac6badcd7d9b5cdb34335f, >= 4710317891e4824ce1510a6b5066abbd3e917750 < 5f4d2bd028ebb6e4c09a9d64842546022321d4a7, >= 4710317891e4824ce1510a6b5066abbd3e917750 < 0526931b16e5a118d367b7bfce7d797e63f7ac69, >= 4710317891e4824ce1510a6b5066abbd3e917750 < 6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e, >= 2.6.33
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
Not available
CVE-2026-64191 — Linux | SECUFOCUS NOW