{
  "cveId": "CVE-2026-64339",
  "url": "https://patchblox.com/security/cve/CVE-2026-64339",
  "summary": "CVE-2026-64339 is fixed in linux on 1 platform by DEBIAN-CVE-2026-64339 (version 7.1.4-1), released August 7, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  usb: misc: usbio: bound bulk IN response length...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  usb: misc: usbio: bound bulk IN response length to the received transfer  usbio_bulk_msg() copies bpkt_len = le16_to_cpu(bpkt-\u003Elen) bytes out of the bulk IN buffer (usbio-\u003Erxbuf, allocated with size usbio-\u003Erxbuf_len) into the caller\u0027s buffer.  bpkt_len is fully controlled by the device and is only checked against ibuf_len; ibuf_len in turn is checked against usbio-\u003Etxbuf_len, not against rxbuf_len:  \tif ((obuf_len \u003E (usbio-\u003Etxbuf_len - sizeof(*bpkt))) || \t    (ibuf_len \u003E (usbio-\u003Etxbuf_len - sizeof(*bpkt)))) \t\treturn -EMSGSIZE;  txbuf_len and rxbuf_len are taken independently from the bulk OUT and bulk IN endpoint wMaxPacketSize in usbio_probe().  A malicious or malfunctioning device that advertises a large bulk OUT endpoint and a small bulk IN endpoint (e.g. by claiming one of the quirk-free IDs such as the Lattice NX33U, 0x2ac1:0x20cb) therefore makes ibuf_len, and hence the device-supplied bpkt_len, exceed rxbuf_len.  memcpy() then reads up to txbuf_len - rxbuf_len bytes past the end of the rxbuf slab object.  The over-read bytes are handed back to the i2c layer and on to user space through i2c-dev, disclosing adjacent slab memory; with KASAN this is reported as a slab-out-of-bounds read.  The number of bytes actually received is already known: act equals the URB actual_length and is bounded by rxbuf_len.  Reject any response that claims more payload than was received, mirroring the existing \u0022act \u003C sizeof(*bpkt)\u0022 check just above.  The control path (usbio_ctrl_msg()) is not affected: it uses a single buffer (ctrlbuf) for both directions, so its analogous copy can never leave the allocation.  Found by code review.  The out-of-bounds read was confirmed under AddressSanitizer with a faithful userspace model of usbio_bulk_msg()\u0027s receive path (an rxbuf_len-sized buffer, the same act/ibuf_len/bpkt_len checks and the memcpy).  A USB raw-gadget \u002B dummy_hcd reproducer is also available.",
  "published": "2026-07-25T10:17:15Z",
  "severity": "high",
  "cvss": 7.1,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
  "epss": 0.00164,
  "epssPercentile": 0.05651,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.1.4-1",
      "fix": "DEBIAN-CVE-2026-64339",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64339",
      "released": "2026-08-07T15:22:10Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T00:53:09Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}