{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.1.4-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "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's 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 \"act \u003c sizeof(*bpkt)\" 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()'s receive path (an rxbuf_len-sized buffer, the same act/ibuf_len/bpkt_len checks and the memcpy).  A USB raw-gadget + dummy_hcd reproducer is also available.",
  "id": "DEBIAN-CVE-2026-64339",
  "modified": "2026-09-14T16:47:32.819379862Z",
  "published": "2026-07-25T10:17:15.870Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64339"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-64339"
  ]
}