{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89622", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.737Z", "datePublished": "2026-09-11T19:45:20.090Z", "dateUpdated": "2026-10-21T12:47:59.999Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:47:59.999Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nHID: mcp2221: clear rxbuf after I2C/SMBus transfer completes\n\nmcp_i2c_smbus_read() stores the caller-supplied buffer pointer in\nmcp->rxbuf for the duration of a transfer but never clears it when the\ntransfer finishes or times out. Once the caller frees or reuses the\nbuffer, mcp->rxbuf becomes a dangling pointer. A delayed or spurious\nMCP2221_I2C_GET_DATA report can then drive mcp2221_raw_event() to\nmemcpy device data into the freed memory, causing a write\nuse-after-free.\n\nRoute all return paths through a single exit point that clears\nmcp->rxbuf and mcp->rxbuf_size, so that the existing !mcp->rxbuf guard\nin the raw_event handler can reject any report arriving after the\ntransfer has ended." } ], "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 - A local attacker can bind hid-mcp2221 by forging BUS_USB 04d8:00dd via UHID_CREATE2 on /dev/uhid (no hid_is_usb() guard), then issue I2C_RDWR/I2C_SMBUS reads on the resulting /dev/i2c-N so mcp_i2c_smbus_read() leaves mcp->rxbuf dangling; a malicious USB MCP2221 is only a lower-severity physical path.\nAC:L - The attacker controls both sides: they start the I2C/SMBus read that stores the bounce buffer in mcp->rxbuf, let mcp_i2c_smbus_read() return without clearing it (timeout or completed xfer), then inject a delayed MCP2221_I2C_GET_DATA report via UHID_INPUT so mcp2221_raw_event() memcpy's into the already-freed buffer.\nPR:L - Neither uhid_dev_create2() nor i2cdev_open() checks capabilities; access is DAC on /dev/uhid and /dev/i2c-*, which udev uaccess-tags for the seat user and which are commonly 0660 root:i2c on embedded/industrial MCP2221 systems, i.e. low privilege rather than real init-namespace root.\nUI:N - The attacker creates the uhid device, issues the I2C/SMBus read ioctl, and injects the delayed HID input report from their own process; no separate victim action is required.\nS:U - The write use-after-free corrupts host-kernel heap or returned SMBus stack under the kernel's own authority and is ordinary local privilege-escalation/DoS, with no VM escape, IOMMU bypass, or other cross-authority impact.\nC:H - mcp2221_raw_event() memcpy's attacker-controlled HID payload into a freed I2C bounce buffer (up to 60 bytes per report, repeatable up to the attacker-chosen rxbuf_size of 8192 via I2C_RDWR); a write UAF of a sprayed slab object yields an arbitrary kernel read primitive.\nI:H - The same memcpy is a write use-after-free of attacker-controlled bytes into freed kernel memory; with heap spraying this is an arbitrary-write and control-flow hijack primitive, so integrity impact is High per UAF guidance.\nA:H - Writing into the freed i2c-dev bounce buffer or returned SMBus stack object can oops or panic the kernel even when not fully exploited, and the dangling mcp->rxbuf persists until the next read so the crash is retriggerable at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/hid/hid-mcp2221.c" ], "versions": [ { "version": "67a95c21463d066060b0f66d65a75d45bb386ffb", "lessThan": "bd146a8ff107c6d77e75597decbcd1df0d7900d6", "status": "affected", "versionType": "git" }, { "version": "67a95c21463d066060b0f66d65a75d45bb386ffb", "lessThan": "d6c6b293173c0ea87189501cbd77e8fa677814a1", "status": "affected", "versionType": "git" }, { "version": "67a95c21463d066060b0f66d65a75d45bb386ffb", "lessThan": "03c34309eb1bce1b3b5f7c4a94b703f419120383", "status": "affected", "versionType": "git" }, { "version": "67a95c21463d066060b0f66d65a75d45bb386ffb", "lessThan": "968546b676d992dd1da3e057d40598231f725996", "status": "affected", "versionType": "git" }, { "version": "67a95c21463d066060b0f66d65a75d45bb386ffb", "lessThan": "db2333f88729c8aae062cb171ed058725ff5c901", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/hid/hid-mcp2221.c" ], "versions": [ { "version": "5.7", "status": "affected" }, { "version": "0", "lessThan": "5.7", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.51", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "5.7", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.18.51" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/bd146a8ff107c6d77e75597decbcd1df0d7900d6" }, { "url": "https://git.kernel.org/stable/c/d6c6b293173c0ea87189501cbd77e8fa677814a1" }, { "url": "https://git.kernel.org/stable/c/03c34309eb1bce1b3b5f7c4a94b703f419120383" }, { "url": "https://git.kernel.org/stable/c/968546b676d992dd1da3e057d40598231f725996" }, { "url": "https://git.kernel.org/stable/c/db2333f88729c8aae062cb171ed058725ff5c901" } ], "title": "HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes", "x_generator": { "engine": "bippy-1.2.0" } } } }