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CVE-2026-53194

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: USB: serial: kl5kusb105: fix bulk-out buffer overflow klsi_105_prepare_write_buffer() is called by the generic write path with the bulk-out buffer and its size (bulk_out_size, 64 bytes). It stores a two-byte length header at the start of the buffer and copies the payload from the write fifo starting at buf + KLSI_HDR_LEN, but passes the full buffer size as the number of bytes to copy: count = kfifo_out_locked(&port->write_fifo, buf + KLSI_HDR_LEN, size, &port->lock); When the fifo holds at least size bytes, size bytes are copied starting two bytes into the size-byte buffer, writing KLSI_HDR_LEN bytes past its end. Copy at most size - KLSI_HDR_LEN bytes instead, leaving room for the header as safe_serial already does. Writing bulk_out_size or more bytes to the tty triggers a slab out-of-bounds write, observed with KASAN by emulating the device with dummy_hcd and raw-gadget: BUG: KASAN: slab-out-of-bounds in kfifo_copy_out+0x83/0xc0 Write of size 64 at addr ffff888112c62202 by task python3 kfifo_copy_out klsi_105_prepare_write_buffer [kl5kusb105] usb_serial_generic_write_start [usbserial] Allocated by task 139: usb_serial_probe [usbserial] The buggy address is located 2 bytes inside of allocated 64-byte region The out-of-bounds write no longer occurs with this change applied.

Severity
HIGH
CVSS score
7.8 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-06-25 09:16:36.850000
Last modified
2026-10-19 20:19:08.480000
View original CVE JSON 
{
  "id": "CVE-2026-53194",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-06-25T09:16:36.850",
  "lastModified": "2026-10-19T20:19:08.480",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: serial: kl5kusb105: fix bulk-out buffer overflow\n\nklsi_105_prepare_write_buffer() is called by the generic write path\nwith the bulk-out buffer and its size (bulk_out_size, 64 bytes). It\nstores a two-byte length header at the start of the buffer and copies\nthe payload from the write fifo starting at buf + KLSI_HDR_LEN, but\npasses the full buffer size as the number of bytes to copy:\n\n  count = kfifo_out_locked(&port->write_fifo, buf + KLSI_HDR_LEN,\n                           size, &port->lock);\n\nWhen the fifo holds at least size bytes, size bytes are copied starting\ntwo bytes into the size-byte buffer, writing KLSI_HDR_LEN bytes past its\nend. Copy at most size - KLSI_HDR_LEN bytes instead, leaving room for\nthe header as safe_serial already does.\n\nWriting bulk_out_size or more bytes to the tty triggers a slab\nout-of-bounds write, observed with KASAN by emulating the device with\ndummy_hcd and raw-gadget:\n\n  BUG: KASAN: slab-out-of-bounds in kfifo_copy_out+0x83/0xc0\n  Write of size 64 at addr ffff888112c62202 by task python3\n   kfifo_copy_out\n   klsi_105_prepare_write_buffer [kl5kusb105]\n   usb_serial_generic_write_start [usbserial]\n  Allocated by task 139:\n   usb_serial_probe [usbserial]\n  The buggy address is located 2 bytes inside of allocated 64-byte region\n\nThe out-of-bounds write no longer occurs with this change applied."
    }
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