CVE-2026-89622 (GCVE-0-2026-89622)
Vulnerability from cvelistv5
Published
2026-09-11 19:45
Modified
2026-10-21 12:47
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes mcp_i2c_smbus_read() stores the caller-supplied buffer pointer in mcp->rxbuf for the duration of a transfer but never clears it when the transfer finishes or times out. Once the caller frees or reuses the buffer, mcp->rxbuf becomes a dangling pointer. A delayed or spurious MCP2221_I2C_GET_DATA report can then drive mcp2221_raw_event() to memcpy device data into the freed memory, causing a write use-after-free. Route all return paths through a single exit point that clears mcp->rxbuf and mcp->rxbuf_size, so that the existing !mcp->rxbuf guard in the raw_event handler can reject any report arriving after the transfer has ended.
References
Impacted products
Vendor Product Version
Linux Linux Version: 67a95c21463d066060b0f66d65a75d45bb386ffb
Version: 67a95c21463d066060b0f66d65a75d45bb386ffb
Version: 67a95c21463d066060b0f66d65a75d45bb386ffb
Version: 67a95c21463d066060b0f66d65a75d45bb386ffb
Version: 67a95c21463d066060b0f66d65a75d45bb386ffb
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/hid/hid-mcp2221.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/hid/hid-mcp2221.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.7"
            },
            {
              "lessThan": "5.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
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            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "5.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "5.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.51",
                  "versionStartIncluding": "5.7",
                  "vulnerable": true
                },
                {
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003erxbuf 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-\u003erxbuf 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-\u003erxbuf and mcp-\u003erxbuf_size, so that the existing !mcp-\u003erxbuf guard\nin the raw_event handler can reject any report arriving after the\ntransfer has ended."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "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-\u003erxbuf 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-\u003erxbuf, 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\u0027s 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\u0027s 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\u0027s 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-\u003erxbuf persists until the next read so the crash is retriggerable at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:47:59.999Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89622",
    "datePublished": "2026-09-11T19:45:20.090Z",
    "dateReserved": "2026-09-11T19:38:34.737Z",
    "dateUpdated": "2026-10-21T12:47:59.999Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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