GHSA-V33C-VVWM-9MR7

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-25 12:31
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

Input: touchwin - reset the packet index on every complete packet

tw_interrupt() accumulates each non-zero serial byte into a fixed three-byte buffer with a running index that is only reset once a full packet has been received and the device's two Y bytes agree:

tw->data[tw->idx++] = data;
if (tw->idx == TW_LENGTH && tw->data[1] == tw->data[2]) {
    ...
    tw->idx = 0;
}

The reset is gated on tw->data[1] == tw->data[2], a value the device controls. A malicious, malfunctioning or counterfeit Touchwindow peripheral can stream non-zero bytes whose 2nd and 3rd bytes differ: the index reaches TW_LENGTH without the equality holding, is never reset, and keeps growing, so tw->data[tw->idx++] walks off the end of the three-byte array and the rest of the heap-allocated struct tw, one attacker-chosen byte at a time -- an unbounded, device-driven heap out-of-bounds write.

Reset the index on every completed packet and report an event only when the two Y bytes match, like the other serio touchscreen drivers do.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-64271"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:07Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nInput: touchwin - reset the packet index on every complete packet\n\ntw_interrupt() accumulates each non-zero serial byte into a fixed\nthree-byte buffer with a running index that is only reset once a full\npacket has been received *and* the device\u0027s two Y bytes agree:\n\n\ttw-\u003edata[tw-\u003eidx++] = data;\n\tif (tw-\u003eidx == TW_LENGTH \u0026\u0026 tw-\u003edata[1] == tw-\u003edata[2]) {\n\t\t...\n\t\ttw-\u003eidx = 0;\n\t}\n\nThe reset is gated on tw-\u003edata[1] == tw-\u003edata[2], a value the device\ncontrols.  A malicious, malfunctioning or counterfeit Touchwindow\nperipheral can stream non-zero bytes whose 2nd and 3rd bytes differ: the\nindex reaches TW_LENGTH without the equality holding, is never reset, and\nkeeps growing, so tw-\u003edata[tw-\u003eidx++] walks off the end of the three-byte\narray and the rest of the heap-allocated struct tw, one attacker-chosen\nbyte at a time -- an unbounded, device-driven heap out-of-bounds write.\n\nReset the index on every completed packet and report an event only when\nthe two Y bytes match, like the other serio touchscreen drivers do.",
  "id": "GHSA-v33c-vvwm-9mr7",
  "modified": "2026-07-25T12:31:28Z",
  "published": "2026-07-25T12:31:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64271"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/044167cba2384bcd783547ad5e30ecd292b30919"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3e6f007b43e2fc6546e21fa74ee62c38984a6672"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/431ad239f2924dff337c3fccb9246597c1b63185"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/478cdd736f2ce3114f90e775d7358136d3977b94"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6c9f29f128dd4057404838259af4c645318487e1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/70e4248793762df9832fd4fc2fc6ac7924572c36"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a8d87184576c889759e3aab899799a482f1e1a5b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ed9b66905407eb3d02df1aaeed82eb7a7f0eb508"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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