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CVE-2026-89622 (GCVE-0-2026-89622)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-13 06:32
VLAI
Title
HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes
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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 67a95c21463d066060b0f66d65a75d45bb386ffb , < 03c34309eb1bce1b3b5f7c4a94b703f419120383 (git)
Affected: 67a95c21463d066060b0f66d65a75d45bb386ffb , < 968546b676d992dd1da3e057d40598231f725996 (git)
Affected: 67a95c21463d066060b0f66d65a75d45bb386ffb , < db2333f88729c8aae062cb171ed058725ff5c901 (git)
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Linux Linux Affected: 5.7
Unaffected: 0 , < 5.7 (semver)
Unaffected: 6.18.51 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/hid/hid-mcp2221.c"
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          "vendor": "Linux",
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          "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."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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          },
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              "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": "2026-09-13T06:32:02.209Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/03c34309eb1bce1b3b5f7c4a94b703f419120383"
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        },
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89622",
    "datePublished": "2026-09-11T19:45:20.090Z",
    "dateReserved": "2026-09-11T19:38:34.737Z",
    "dateUpdated": "2026-09-13T06:32:02.209Z",
    "state": "PUBLISHED"
  },
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      "percentile": "0.05216"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-14T09:58:49+00:00",
      "cve": "CVE-2026-89622",
      "id": "CVE-2026-89622",
      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_not_affected": "276",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89622.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-16T00:01:29Z",
      "cve": "CVE-2026-89622",
      "id": "CVE-2026-89622",
      "initial_release_date": "2026-09-12T16:24:51Z",
      "product_status:known_affected": "210",
      "product_status:known_not_affected": "143",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89622",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89622.json",
      "version": "4"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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