{"api_version":"1","generated_at":"2026-07-23T11:24:40+00:00","cve":"CVE-2026-64191","urls":{"html":"https://cve.report/CVE-2026-64191","api":"https://cve.report/api/cve/CVE-2026-64191.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64191","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64191"},"summary":{"title":"i2c: stub: Reject I2C block transfers with invalid length","description":"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().","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-20 17:18:22","updated_at":"2026-07-20 17:18:22"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/1c4ffe6b4f04365485ed58d64c9bb86b46fc9037","name":"https://git.kernel.org/stable/c/1c4ffe6b4f04365485ed58d64c9bb86b46fc9037","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0526931b16e5a118d367b7bfce7d797e63f7ac69","name":"https://git.kernel.org/stable/c/0526931b16e5a118d367b7bfce7d797e63f7ac69","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5f4d2bd028ebb6e4c09a9d64842546022321d4a7","name":"https://git.kernel.org/stable/c/5f4d2bd028ebb6e4c09a9d64842546022321d4a7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3fd225f3e4cd67ec8ddab1afed9da03c7c43537c","name":"https://git.kernel.org/stable/c/3fd225f3e4cd67ec8ddab1afed9da03c7c43537c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7e9072dbd5f2f17934751873450d2c22080ead80","name":"https://git.kernel.org/stable/c/7e9072dbd5f2f17934751873450d2c22080ead80","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/21e87f336ac6303fed54a69b1d0d79a23b25c8d0","name":"https://git.kernel.org/stable/c/21e87f336ac6303fed54a69b1d0d79a23b25c8d0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e","name":"https://git.kernel.org/stable/c/6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4bd8635f28c135a08aac6badcd7d9b5cdb34335f","name":"https://git.kernel.org/stable/c/4bd8635f28c135a08aac6badcd7d9b5cdb34335f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64191","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64191","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4710317891e4824ce1510a6b5066abbd3e917750 7e9072dbd5f2f17934751873450d2c22080ead80 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4710317891e4824ce1510a6b5066abbd3e917750 21e87f336ac6303fed54a69b1d0d79a23b25c8d0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4710317891e4824ce1510a6b5066abbd3e917750 3fd225f3e4cd67ec8ddab1afed9da03c7c43537c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4710317891e4824ce1510a6b5066abbd3e917750 1c4ffe6b4f04365485ed58d64c9bb86b46fc9037 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4710317891e4824ce1510a6b5066abbd3e917750 4bd8635f28c135a08aac6badcd7d9b5cdb34335f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4710317891e4824ce1510a6b5066abbd3e917750 5f4d2bd028ebb6e4c09a9d64842546022321d4a7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4710317891e4824ce1510a6b5066abbd3e917750 0526931b16e5a118d367b7bfce7d797e63f7ac69 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4710317891e4824ce1510a6b5066abbd3e917750 6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.33","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.33 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.260 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.211 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.177 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.144 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.95 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.37 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.14 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"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->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()."}],"providerMetadata":{"dateUpdated":"2026-07-20T16:27:51.120Z","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":"2026-07-20T16:27:51.120Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-20 17:18:22","lastModifiedDate":"2026-07-20 17:18:22","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64191","Ordinal":"1","Title":"i2c: stub: Reject I2C block transfers with invalid length","CVE":"CVE-2026-64191","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64191","Ordinal":"1","NoteData":"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().","Type":"Description","Title":"i2c: stub: Reject I2C block transfers with invalid length"}]}}}