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vuln-cve/data/2026/64xxx/CVE-2026-64191.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-64191",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-07-19T07:54:57.040Z",
"datePublished": "2026-07-20T16:27:51.120Z",
"dateUpdated": "2026-10-19T20:28:15.069Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-08-05T12:39:59.861Z"
},
"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->block[0]\nas the transfer length. The existing check only clamps it to avoid\noverrunning the chip->words[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->block[0] > 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 <TASK>\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 </TASK>\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->block[0] == 0 or\ndata->block[0] > 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": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH"
},
"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."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/i2c/i2c-stub.c"
],
"versions": [
{
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "7e9072dbd5f2f17934751873450d2c22080ead80",
"status": "affected",
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},
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},
{
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]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/i2c/i2c-stub.c"
],
"versions": [
{
"version": "2.6.33",
"status": "affected"
},
{
"version": "0",
"lessThan": "2.6.33",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.10.260",
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
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},
{
"version": "5.15.211",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
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},
{
"version": "6.1.177",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
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},
{
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"lessThanOrEqual": "6.6.*",
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},
{
"version": "6.12.95",
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.18.37",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.0.14",
"lessThanOrEqual": "7.0.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.1",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.33",
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{
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},
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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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}
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],
"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"
}
},
"adp": [
{
"metrics": [
{
"other": {
"type": "ssvc",
"content": {
"id": "CVE-2026-64191",
"role": "CISA Coordinator",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-10-16T15:37:24.187565Z"
}
}
}
],
"problemTypes": [
{
"descriptions": [
{
"lang": "en",
"type": "CWE",
"cweId": "CWE-787",
"description": "CWE-787 Out-of-bounds Write"
}
]
}
],
"title": "CISA ADP Vulnrichment",
"providerMetadata": {
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP",
"dateUpdated": "2026-10-19T20:28:15.069Z"
}
}
]
}
}