{"id":"CVE-2026-72141","state":"PUBLISHED","title":"i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)\n\nSMBus 3.1 6.5.7 allows a Block Read byte count of 0, but the\ninterrupt-driven block-read state machine rejects it as -EPROTO. Worse,\nit returns without a NACK+STOP: the next receive cycle has already\nstarted, so the target keeps holding SDA and the bus stays stuck until a\npower cycle of this i2c controller.\n\nAccept count=0: NACK the in-flight dummy byte (TXAK) and set msg->len to\n2 so i2c_imx_isr_read_continue() emits STOP via its normal last-byte\npath. The dummy byte is discarded; block-read callers only consume\nbuf[0..count-1].\n\nReading I2DR has likewise already armed the next byte on the\ncount > I2C_SMBUS_BLOCK_MAX error path, so NACK it (TXAK) before aborting\nwith -EPROTO; otherwise the failing transfer's STOP cannot complete and\nthe bus stays held.\n\nThe atomic path regressed earlier (v3.16) and is fixed separately; this\npatch covers only the v6.13 state-machine rework.","publishedAt":"2026-08-15T05:53:14.754Z","updatedAt":"2026-08-17T05:40:49.962Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5f5c2d4579ca6836f5604cca979debd68ecfe23f","status":"affected","lessThan":"5d3240f42a667e29262aff76fdebfcdac4980626","versionType":"git"},{"version":"5f5c2d4579ca6836f5604cca979debd68ecfe23f","status":"affected","lessThan":"56ddfc18ea8f7d77747658892873eb632b2ed530","versionType":"git"},{"version":"5f5c2d4579ca6836f5604cca979debd68ecfe23f","status":"affected","lessThan":"07fd9385f0d87dff4b34f355f68adf701080cb24","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/i2c/busses/i2c-imx.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.13","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/i2c/busses/i2c-imx.c"]}],"references":["https://git.kernel.org/stable/c/5d3240f42a667e29262aff76fdebfcdac4980626","https://git.kernel.org/stable/c/56ddfc18ea8f7d77747658892873eb632b2ed530","https://git.kernel.org/stable/c/07fd9385f0d87dff4b34f355f68adf701080cb24"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72141.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72141","state":"PUBLISHED","datePublished":"2026-08-15T05:53:14.754Z","dateUpdated":"2026-08-17T05:40:49.962Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.908Z"},"containers":{"cna":{"title":"i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)\n\nSMBus 3.1 6.5.7 allows a Block Read byte count of 0, but the\ninterrupt-driven block-read state machine rejects it as -EPROTO. Worse,\nit returns without a NACK+STOP: the next receive cycle has already\nstarted, so the target keeps holding SDA and the bus stays stuck until a\npower cycle of this i2c controller.\n\nAccept count=0: NACK the in-flight dummy byte (TXAK) and set msg->len to\n2 so i2c_imx_isr_read_continue() emits STOP via its normal last-byte\npath. The dummy byte is discarded; block-read callers only consume\nbuf[0..count-1].\n\nReading I2DR has likewise already armed the next byte on the\ncount > I2C_SMBUS_BLOCK_MAX error path, so NACK it (TXAK) before aborting\nwith -EPROTO; otherwise the failing transfer's STOP cannot complete and\nthe bus stays held.\n\nThe atomic path regressed earlier (v3.16) and is fixed separately; this\npatch covers only the v6.13 state-machine rework."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5f5c2d4579ca6836f5604cca979debd68ecfe23f","status":"affected","lessThan":"5d3240f42a667e29262aff76fdebfcdac4980626","versionType":"git"},{"version":"5f5c2d4579ca6836f5604cca979debd68ecfe23f","status":"affected","lessThan":"56ddfc18ea8f7d77747658892873eb632b2ed530","versionType":"git"},{"version":"5f5c2d4579ca6836f5604cca979debd68ecfe23f","status":"affected","lessThan":"07fd9385f0d87dff4b34f355f68adf701080cb24","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/i2c/busses/i2c-imx.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.13","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/i2c/busses/i2c-imx.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/5d3240f42a667e29262aff76fdebfcdac4980626"},{"url":"https://git.kernel.org/stable/c/56ddfc18ea8f7d77747658892873eb632b2ed530"},{"url":"https://git.kernel.org/stable/c/07fd9385f0d87dff4b34f355f68adf701080cb24"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - On NXP Layerscape/i.MX appliances, remotely reachable IPMI-over-LAN or management-plane requests invoke ipmi_ssif/pmbus i2c_smbus_read_block_data() on imx-i2c; a malicious or compromised bus peripheral returning SMBus block-read count 0 reaches the vulnerable IRQ handler without local login.\nAC:L - Once an SMBus block-read transaction is initiated and the target returns count byte 0 (a valid SMBus 3.1 response), the IRQ path deterministically omits NACK/STOP and locks the bus; the attacker controls both transaction initiation and slave response via compromised BMC/PMBus device or planted peripheral.\nPR:N - No Linux credentials are required when a malicious or compromised I2C slave returns count 0 during kernel-initiated SMBus block reads from IPMI SSIF, PMBus hwmon polling, or other automated drivers; OS privilege is not needed beyond influencing the bus response.\nUI:N - Exploitation requires no victim interaction because kernel subsystems (IPMI SSIF, PMBus hwmon, sensor drivers) automatically perform SMBus block reads during normal remote-management or background monitoring operations once the bus device responds.\nS:U - Impact is confined to locking the imx-i2c controller and attached I2C bus within the same kernel/host security boundary; it does not cross VM, container, or IOMMU isolation boundaries.\nC:N - The flaw is a missing NACK/STOP during SMBus block-read length handling; it causes a stuck I2C bus but does not corrupt kernel memory, leak data, or provide read primitives.\nI:N - No kernel or user data is modified; the bug only leaves the I2C controller in a hung bus state without write primitives, code execution, or integrity violations beyond loss of bus function.\nA:H - A successful trigger permanently locks the imx-i2c bus until controller power-cycle, denying all further I2C/SMBus communication to PMICs, sensors, EEPROMs, and BMC SSIF on safety-critical embedded, automotive, and datacenter systems."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:40:49.962Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}