Vulnerability-Lookup

FKIE_CVE-2026-64191

Vulnerability from fkie_nvd - Published: 2026-07-20 17:18 - Updated: 2026-10-19 21:17

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

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().

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/0526931b16e5a118d367b7bfce7d797e63f7ac69	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/1c4ffe6b4f04365485ed58d64c9bb86b46fc9037	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/21e87f336ac6303fed54a69b1d0d79a23b25c8d0	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/3fd225f3e4cd67ec8ddab1afed9da03c7c43537c	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/4bd8635f28c135a08aac6badcd7d9b5cdb34335f	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/5f4d2bd028ebb6e4c09a9d64842546022321d4a7	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7e9072dbd5f2f17934751873450d2c22080ead80	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	7.1
linux	linux_kernel	7.1

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/i2c/i2c-stub.c"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "5.10.260",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "5.15.211",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.37",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.14",
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            {
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    }
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: stub: Reject I2C block transfers with invalid length\n\nThe I2C_SMBUS_I2C_BLOCK_DATA case in stub_xfer() uses data-\u003eblock[0]\nas the transfer length. The existing check only clamps it to avoid\noverrunning the chip-\u003ewords[256] register array, but does not validate\nit against I2C_SMBUS_BLOCK_MAX (32), which is the limit of the union\ni2c_smbus_data.block buffer (34 bytes total). The driver is a\ndevelopment/test tool (CONFIG_I2C_STUB=m, not built by default)\nthat must be loaded with a chip_addr= parameter.\n\nA local user with access to /dev/i2c-* can issue an I2C_SMBUS ioctl\nwith I2C_SMBUS_I2C_BLOCK_DATA and data-\u003eblock[0] \u003e 32, causing\nstub_xfer() to read or write past the end of the union\ni2c_smbus_data.block buffer:\n\n BUG: KASAN: stack-out-of-bounds in stub_xfer (drivers/i2c/i2c-stub.c:223)\n Read of size 1 at addr ffff88800abcfd92 by task exploit/81\n Call Trace:\n  \u003cTASK\u003e\n  stub_xfer (drivers/i2c/i2c-stub.c:223)\n  __i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:593)\n  i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:536)\n  i2cdev_ioctl_smbus (drivers/i2c/i2c-dev.c:391)\n  i2cdev_ioctl (drivers/i2c/i2c-dev.c:478)\n  __x64_sys_ioctl (fs/ioctl.c:583)\n  do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n  \u003c/TASK\u003e\n\nThe bug exists because i2c-stub implements .smbus_xfer directly,\nbypassing the I2C_SMBUS_BLOCK_MAX validation in\ni2c_smbus_xfer_emulated(). The I2C_SMBUS_BLOCK_DATA case in the same\nfunction correctly validates against I2C_SMBUS_BLOCK_MAX, but the\nI2C_SMBUS_I2C_BLOCK_DATA case does not.\n\nFix by rejecting transfers with data-\u003eblock[0] == 0 or\ndata-\u003eblock[0] \u003e I2C_SMBUS_BLOCK_MAX with -EINVAL, consistent with\nboth the I2C_SMBUS_BLOCK_DATA case in the same function and the\nI2C_SMBUS_I2C_BLOCK_DATA validation in i2c_smbus_xfer_emulated()."
    }
  ],
  "id": "CVE-2026-64191",
  "lastModified": "2026-10-19T21:17:26.730",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-64191",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T15:37:24.187565Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-20T17:18:22.217",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/0526931b16e5a118d367b7bfce7d797e63f7ac69"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/1c4ffe6b4f04365485ed58d64c9bb86b46fc9037"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/21e87f336ac6303fed54a69b1d0d79a23b25c8d0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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      "url": "https://git.kernel.org/stable/c/3fd225f3e4cd67ec8ddab1afed9da03c7c43537c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/4bd8635f28c135a08aac6badcd7d9b5cdb34335f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/5f4d2bd028ebb6e4c09a9d64842546022321d4a7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "Patch"
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      "url": "https://git.kernel.org/stable/c/7e9072dbd5f2f17934751873450d2c22080ead80"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-787"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}

CVE-2026-64191 (GCVE-0-2026-64191)

Vulnerability from cvelistv5 – Published: 2026-07-20 16:27 – Updated: 2026-10-19 20:28

Title

i2c: stub: Reject I2C block transfers with invalid length

Summary

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-16 15:37 UTC

CWE

CWE-787 - Out-of-bounds Write

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7061 records in the last 180 days details

References

8 references

URL	Tags
https://git.kernel.org/stable/c/7e9072dbd5f2f1793…
https://git.kernel.org/stable/c/21e87f336ac6303fe…
https://git.kernel.org/stable/c/3fd225f3e4cd67ec8…
https://git.kernel.org/stable/c/1c4ffe6b4f0436548…
https://git.kernel.org/stable/c/4bd8635f28c135a08…
https://git.kernel.org/stable/c/5f4d2bd028ebb6e4c…
https://git.kernel.org/stable/c/0526931b16e5a118d…
https://git.kernel.org/stable/c/6036b5067a8199ba7…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 4710317891e4824ce1510a6b5066abbd3e917750 , < 7e9072dbd5f2f17934751873450d2c22080ead80 (git) Affected: 4710317891e4824ce1510a6b5066abbd3e917750 , < 21e87f336ac6303fed54a69b1d0d79a23b25c8d0 (git) Affected: 4710317891e4824ce1510a6b5066abbd3e917750 , < 3fd225f3e4cd67ec8ddab1afed9da03c7c43537c (git) Affected: 4710317891e4824ce1510a6b5066abbd3e917750 , < 1c4ffe6b4f04365485ed58d64c9bb86b46fc9037 (git) Affected: 4710317891e4824ce1510a6b5066abbd3e917750 , < 4bd8635f28c135a08aac6badcd7d9b5cdb34335f (git) Affected: 4710317891e4824ce1510a6b5066abbd3e917750 , < 5f4d2bd028ebb6e4c09a9d64842546022321d4a7 (git) Affected: 4710317891e4824ce1510a6b5066abbd3e917750 , < 0526931b16e5a118d367b7bfce7d797e63f7ac69 (git) Affected: 4710317891e4824ce1510a6b5066abbd3e917750 , < 6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e (git)
Linux	Linux	Affected: 2.6.33 Unaffected: 0 , < 2.6.33 (semver) Unaffected: 5.10.260 , ≤ 5.10.* (semver) Unaffected: 5.15.211 , ≤ 5.15.* (semver) Unaffected: 6.1.177 , ≤ 6.1.* (semver) Unaffected: 6.6.144 , ≤ 6.6.* (semver) Unaffected: 6.12.95 , ≤ 6.12.* (semver) Unaffected: 6.18.37 , ≤ 6.18.* (semver) Unaffected: 7.0.14 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-64191",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T15:37:24.187565Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-787",
                "description": "CWE-787 Out-of-bounds Write",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-19T20:28:15.069Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/i2c/i2c-stub.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7e9072dbd5f2f17934751873450d2c22080ead80",
              "status": "affected",
              "version": "4710317891e4824ce1510a6b5066abbd3e917750",
              "versionType": "git"
            },
            {
              "lessThan": "21e87f336ac6303fed54a69b1d0d79a23b25c8d0",
              "status": "affected",
              "version": "4710317891e4824ce1510a6b5066abbd3e917750",
              "versionType": "git"
            },
            {
              "lessThan": "3fd225f3e4cd67ec8ddab1afed9da03c7c43537c",
              "status": "affected",
              "version": "4710317891e4824ce1510a6b5066abbd3e917750",
              "versionType": "git"
            },
            {
              "lessThan": "1c4ffe6b4f04365485ed58d64c9bb86b46fc9037",
              "status": "affected",
              "version": "4710317891e4824ce1510a6b5066abbd3e917750",
              "versionType": "git"
            },
            {
              "lessThan": "4bd8635f28c135a08aac6badcd7d9b5cdb34335f",
              "status": "affected",
              "version": "4710317891e4824ce1510a6b5066abbd3e917750",
              "versionType": "git"
            },
            {
              "lessThan": "5f4d2bd028ebb6e4c09a9d64842546022321d4a7",
              "status": "affected",
              "version": "4710317891e4824ce1510a6b5066abbd3e917750",
              "versionType": "git"
            },
            {
              "lessThan": "0526931b16e5a118d367b7bfce7d797e63f7ac69",
              "status": "affected",
              "version": "4710317891e4824ce1510a6b5066abbd3e917750",
              "versionType": "git"
            },
            {
              "lessThan": "6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e",
              "status": "affected",
              "version": "4710317891e4824ce1510a6b5066abbd3e917750",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/i2c/i2c-stub.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.33"
            },
            {
              "lessThan": "2.6.33",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.260",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.211",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.37",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.260",
                  "versionStartIncluding": "2.6.33",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.211",
                  "versionStartIncluding": "2.6.33",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.177",
                  "versionStartIncluding": "2.6.33",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.144",
                  "versionStartIncluding": "2.6.33",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.95",
                  "versionStartIncluding": "2.6.33",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.37",
                  "versionStartIncluding": "2.6.33",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.14",
                  "versionStartIncluding": "2.6.33",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "2.6.33",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: stub: Reject I2C block transfers with invalid length\n\nThe I2C_SMBUS_I2C_BLOCK_DATA case in stub_xfer() uses data-\u003eblock[0]\nas the transfer length. The existing check only clamps it to avoid\noverrunning the chip-\u003ewords[256] register array, but does not validate\nit against I2C_SMBUS_BLOCK_MAX (32), which is the limit of the union\ni2c_smbus_data.block buffer (34 bytes total). The driver is a\ndevelopment/test tool (CONFIG_I2C_STUB=m, not built by default)\nthat must be loaded with a chip_addr= parameter.\n\nA local user with access to /dev/i2c-* can issue an I2C_SMBUS ioctl\nwith I2C_SMBUS_I2C_BLOCK_DATA and data-\u003eblock[0] \u003e 32, causing\nstub_xfer() to read or write past the end of the union\ni2c_smbus_data.block buffer:\n\n BUG: KASAN: stack-out-of-bounds in stub_xfer (drivers/i2c/i2c-stub.c:223)\n Read of size 1 at addr ffff88800abcfd92 by task exploit/81\n Call Trace:\n  \u003cTASK\u003e\n  stub_xfer (drivers/i2c/i2c-stub.c:223)\n  __i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:593)\n  i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:536)\n  i2cdev_ioctl_smbus (drivers/i2c/i2c-dev.c:391)\n  i2cdev_ioctl (drivers/i2c/i2c-dev.c:478)\n  __x64_sys_ioctl (fs/ioctl.c:583)\n  do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n  \u003c/TASK\u003e\n\nThe bug exists because i2c-stub implements .smbus_xfer directly,\nbypassing the I2C_SMBUS_BLOCK_MAX validation in\ni2c_smbus_xfer_emulated(). The I2C_SMBUS_BLOCK_DATA case in the same\nfunction correctly validates against I2C_SMBUS_BLOCK_MAX, but the\nI2C_SMBUS_I2C_BLOCK_DATA case does not.\n\nFix by rejecting transfers with data-\u003eblock[0] == 0 or\ndata-\u003eblock[0] \u003e I2C_SMBUS_BLOCK_MAX with -EINVAL, consistent with\nboth the I2C_SMBUS_BLOCK_DATA case in the same function and the\nI2C_SMBUS_I2C_BLOCK_DATA validation in i2c_smbus_xfer_emulated()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable path is reached by a local process issuing I2C_SMBUS ioctls on an i2c-stub /dev/i2c-* character device; it is neither remotely nor physically reachable.\nAC:L - Once i2c-stub is loaded, the attacker controls the address, direction, length, and register contents, making the corruption deterministic without a race. The non-default module configuration defines the vulnerable deployment rather than complicating exploitation within it.\nPR:L - The attacker needs unprivileged local access to the applicable /dev/i2c-* node, but no capability or namespace-specific administrative privilege is checked anywhere along the ioctl path.\nUI:N - After the vulnerable adapter is configured, exploitation requires only attacker-issued ioctls and no action by another user.\nS:U - The corruption occurs within the host kernel and represents conventional local privilege escalation, without crossing a separate virtualization or hardware security authority.\nC:H - An oversized block write reads up to 222 bytes beyond the 34-byte stack union and persists those bytes in attacker-readable stub registers, enabling substantial kernel-stack disclosure.\nI:H - An oversized block read writes up to 222 attacker-chosen bytes beyond the stack union because the attacker can prepopulate the stub registers, enabling control-data corruption and potential kernel code execution.\nA:H - The controlled stack overwrite can corrupt stack canaries, return state, or other control data, causing a repeatable kernel oops or panic even when code execution is unsuccessful."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:39:59.861Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/7e9072dbd5f2f17934751873450d2c22080ead80"
        },
        {
          "url": "https://git.kernel.org/stable/c/21e87f336ac6303fed54a69b1d0d79a23b25c8d0"
        },
        {
          "url": "https://git.kernel.org/stable/c/3fd225f3e4cd67ec8ddab1afed9da03c7c43537c"
        },
        {
          "url": "https://git.kernel.org/stable/c/1c4ffe6b4f04365485ed58d64c9bb86b46fc9037"
        },
        {
          "url": "https://git.kernel.org/stable/c/4bd8635f28c135a08aac6badcd7d9b5cdb34335f"
        },
        {
          "url": "https://git.kernel.org/stable/c/5f4d2bd028ebb6e4c09a9d64842546022321d4a7"
        },
        {
          "url": "https://git.kernel.org/stable/c/0526931b16e5a118d367b7bfce7d797e63f7ac69"
        },
        {
          "url": "https://git.kernel.org/stable/c/6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e"
        }
      ],
      "title": "i2c: stub: Reject I2C block transfers with invalid length",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64191",
    "datePublished": "2026-07-20T16:27:51.120Z",
    "dateReserved": "2026-07-19T07:54:57.040Z",
    "dateUpdated": "2026-10-19T20:28:15.069Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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