CVE-2026-64191i2c: stub: Reject I2C block transfers with invalid length
- 7.8HighCVSS base score
- 0.17%Exploitation in 30 daysEPSS · top 94% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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().
Timeline
ID reserved
By Linux
- 1 day later
· 1 day later
Published
- 3 months later
· 3 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.17% · top 94% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 4710317891e4824ce1510a6b5066abbd3e917750 – < 7e9072dbd5f2f17934751873450d2c22080ead80
- affected 4710317891e4824ce1510a6b5066abbd3e917750 – < 21e87f336ac6303fed54a69b1d0d79a23b25c8d0
- affected 4710317891e4824ce1510a6b5066abbd3e917750 – < 3fd225f3e4cd67ec8ddab1afed9da03c7c43537c
- affected 4710317891e4824ce1510a6b5066abbd3e917750 – < 1c4ffe6b4f04365485ed58d64c9bb86b46fc9037
- affected 4710317891e4824ce1510a6b5066abbd3e917750 – < 4bd8635f28c135a08aac6badcd7d9b5cdb34335f
- affected 4710317891e4824ce1510a6b5066abbd3e917750 – < 5f4d2bd028ebb6e4c09a9d64842546022321d4a7
- affected 4710317891e4824ce1510a6b5066abbd3e917750 – < 0526931b16e5a118d367b7bfce7d797e63f7ac69
- affected 4710317891e4824ce1510a6b5066abbd3e917750 – < 6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e
- affected 2.6.33
- unaffected < 2.6.33
- unaffected 5.10.260 – ≤ 5.10.*
- unaffected 5.15.211 – ≤ 5.15.*
- unaffected 6.1.177 – ≤ 6.1.*
- unaffected 6.6.144 – ≤ 6.6.*
- unaffected 6.12.95 – ≤ 6.12.*
- unaffected 6.18.37 – ≤ 6.18.*
- unaffected 7.0.14 – ≤ 7.0.*
- unaffected 7.1 – ≤ *
References
References8
- https://git.kernel.org/stable/c/7e9072dbd5f2f17934751873450d2c22080ead80 (opens in a new tab)
- https://git.kernel.org/stable/c/21e87f336ac6303fed54a69b1d0d79a23b25c8d0 (opens in a new tab)
- https://git.kernel.org/stable/c/3fd225f3e4cd67ec8ddab1afed9da03c7c43537c (opens in a new tab)
- https://git.kernel.org/stable/c/1c4ffe6b4f04365485ed58d64c9bb86b46fc9037 (opens in a new tab)
- https://git.kernel.org/stable/c/4bd8635f28c135a08aac6badcd7d9b5cdb34335f (opens in a new tab)
- https://git.kernel.org/stable/c/5f4d2bd028ebb6e4c09a9d64842546022321d4a7 (opens in a new tab)
- https://git.kernel.org/stable/c/0526931b16e5a118d367b7bfce7d797e63f7ac69 (opens in a new tab)
- https://git.kernel.org/stable/c/6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-46011 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-64191)Record last updated .