{"id":"CVE-2026-64086","state":"PUBLISHED","title":"hwmon: (pmbus/adm1266) include PEC byte in pmbus_block_xfer read buffer","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nhwmon: (pmbus/adm1266) include PEC byte in pmbus_block_xfer read buffer\n\nadm1266_pmbus_block_xfer() sets up the read transaction with\n\n\t.buf = data->read_buf,\n\t.len = ADM1266_PMBUS_BLOCK_MAX + 2,\n\nbut read_buf in struct adm1266_data is declared as\n\n\tu8 read_buf[ADM1266_PMBUS_BLOCK_MAX + 1];\n\nFor a max-length block response (length byte = 255 + up to 1 PEC\nbyte), the i2c controller is told to write 257 bytes into a 256-byte\nbuffer, putting one byte past the end of read_buf.  The same response\nalso makes the subsequent PEC compare\n\n\tif (crc != msgs[1].buf[msgs[1].buf[0] + 1])\n\nread a byte beyond the array.\n\nBump the read_buf declaration to ADM1266_PMBUS_BLOCK_MAX + 2 so the\nbuffer can hold the length byte, up to 255 payload bytes, and the PEC\nbyte the i2c_msg length already accounts for.","publishedAt":"2026-07-19T15:39:56.749Z","updatedAt":"2026-08-05T12:39:03.986Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"397d3f523bfff2f4e3dacf9b1339bd76dc207f78","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"472744f69d25a2d5111ad62f1d62579dce2c13c8","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"528a9f88e88502d0c2f2052a279415074cd83715","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"d94ceb16e55b6d8019ab069e357c76ac42f0ffbc","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"bd5be3fa5de6dbf61f1b3cec6b79c2c2f8065694","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"2279c342d94eca225bf9f301c8806a05a1c81619","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"a6c802145a8de0830bca803c6d415f7e9e683624","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"487566cb1ccdf3756fdd7bf8d875e612ff3169bb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/hwmon/pmbus/adm1266.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/hwmon/pmbus/adm1266.c"]}],"references":["https://git.kernel.org/stable/c/397d3f523bfff2f4e3dacf9b1339bd76dc207f78","https://git.kernel.org/stable/c/472744f69d25a2d5111ad62f1d62579dce2c13c8","https://git.kernel.org/stable/c/528a9f88e88502d0c2f2052a279415074cd83715","https://git.kernel.org/stable/c/d94ceb16e55b6d8019ab069e357c76ac42f0ffbc","https://git.kernel.org/stable/c/bd5be3fa5de6dbf61f1b3cec6b79c2c2f8065694","https://git.kernel.org/stable/c/2279c342d94eca225bf9f301c8806a05a1c81619","https://git.kernel.org/stable/c/a6c802145a8de0830bca803c6d415f7e9e683624","https://git.kernel.org/stable/c/487566cb1ccdf3756fdd7bf8d875e612ff3169bb"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64086.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64086","state":"PUBLISHED","datePublished":"2026-07-19T15:39:56.749Z","dateUpdated":"2026-08-05T12:39:03.986Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.032Z"},"containers":{"cna":{"title":"hwmon: (pmbus/adm1266) include PEC byte in pmbus_block_xfer read buffer","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nhwmon: (pmbus/adm1266) include PEC byte in pmbus_block_xfer read buffer\n\nadm1266_pmbus_block_xfer() sets up the read transaction with\n\n\t.buf = data->read_buf,\n\t.len = ADM1266_PMBUS_BLOCK_MAX + 2,\n\nbut read_buf in struct adm1266_data is declared as\n\n\tu8 read_buf[ADM1266_PMBUS_BLOCK_MAX + 1];\n\nFor a max-length block response (length byte = 255 + up to 1 PEC\nbyte), the i2c controller is told to write 257 bytes into a 256-byte\nbuffer, putting one byte past the end of read_buf.  The same response\nalso makes the subsequent PEC compare\n\n\tif (crc != msgs[1].buf[msgs[1].buf[0] + 1])\n\nread a byte beyond the array.\n\nBump the read_buf declaration to ADM1266_PMBUS_BLOCK_MAX + 2 so the\nbuffer can hold the length byte, up to 255 payload bytes, and the PEC\nbyte the i2c_msg length already accounts for."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"397d3f523bfff2f4e3dacf9b1339bd76dc207f78","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"472744f69d25a2d5111ad62f1d62579dce2c13c8","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"528a9f88e88502d0c2f2052a279415074cd83715","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"d94ceb16e55b6d8019ab069e357c76ac42f0ffbc","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"bd5be3fa5de6dbf61f1b3cec6b79c2c2f8065694","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"2279c342d94eca225bf9f301c8806a05a1c81619","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"a6c802145a8de0830bca803c6d415f7e9e683624","versionType":"git"},{"version":"407dc802a9c0809ca6a48de4b4c63305eb84ef56","status":"affected","lessThan":"487566cb1ccdf3756fdd7bf8d875e612ff3169bb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/hwmon/pmbus/adm1266.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/hwmon/pmbus/adm1266.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/397d3f523bfff2f4e3dacf9b1339bd76dc207f78"},{"url":"https://git.kernel.org/stable/c/472744f69d25a2d5111ad62f1d62579dce2c13c8"},{"url":"https://git.kernel.org/stable/c/528a9f88e88502d0c2f2052a279415074cd83715"},{"url":"https://git.kernel.org/stable/c/d94ceb16e55b6d8019ab069e357c76ac42f0ffbc"},{"url":"https://git.kernel.org/stable/c/bd5be3fa5de6dbf61f1b3cec6b79c2c2f8065694"},{"url":"https://git.kernel.org/stable/c/2279c342d94eca225bf9f301c8806a05a1c81619"},{"url":"https://git.kernel.org/stable/c/a6c802145a8de0830bca803c6d415f7e9e683624"},{"url":"https://git.kernel.org/stable/c/487566cb1ccdf3756fdd7bf8d875e612ff3169bb"}],"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 code is only reached through local kernel interfaces (debugfs GPIO dump at /sys/kernel/debug/gpio and root-only nvmem blackbox reads), not through any network protocol handler. The ADM1266 sits on an on-board I2C bus on server BMC hardware.\nAC:L - An attacker who controls the I2C bus response (malicious device, compromised ADM1266 firmware, or bus interposition on the BMC) can reliably force a 255-byte block reply whenever a victim triggers the block-transfer path, causing the one-byte overflow on demand.\nPR:L - The gpio debugfs entry is world-readable (0444) if debugfs is mounted and traversable, which occurs on some embedded BMC images without strict permissions; between requiring full init-namespace root and that lower bar, the less privileged path is plausible on misconfigured systems.\nUI:N - Exploitation does not require victim interaction beyond the attacker (or a compromised daemon) programmatically reading debugfs or nvmem; no mount, click, or plug-in action by an end user is needed.\nS:U - Impact is confined to kernel memory corruption within the BMC/host kernel security boundary; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - The PEC validation performs an out-of-bounds read past read_buf, and the one-byte heap overflow can corrupt adjacent kernel objects in ways that enable further memory disclosure primitives.\nI:H - A one-byte, attacker-controlled out-of-bounds write past the end of read_buf into adjacent heap memory can corrupt slab metadata or neighboring objects and be developed into arbitrary write or code-execution primitives.\nA:H - Corrupting adjacent heap objects via the out-of-bounds write can cause kernel oops, panic, or hang on the BMC, denying management-plane availability for the managed server."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:39:03.986Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"5.10.258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"5.15.209"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.6.142"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.12.92"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}