CVE-2026-31607
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BaseFortify
Publication date: 2026-04-24
Last updated on: 2026-04-28
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
usbip: validate number_of_packets in usbip_pack_ret_submit()
When a USB/IP client receives a RET_SUBMIT response,
usbip_pack_ret_submit() unconditionally overwrites
urb->number_of_packets from the network PDU. This value is
subsequently used as the loop bound in usbip_recv_iso() and
usbip_pad_iso() to iterate over urb->iso_frame_desc[], a flexible
array whose size was fixed at URB allocation time based on the
*original* number_of_packets from the CMD_SUBMIT.
A malicious USB/IP server can set number_of_packets in the response
to a value larger than what was originally submitted, causing a heap
out-of-bounds write when usbip_recv_iso() writes to
urb->iso_frame_desc[i] beyond the allocated region.
KASAN confirmed this with kernel 7.0.0-rc5:
BUG: KASAN: slab-out-of-bounds in usbip_recv_iso+0x46a/0x640
Write of size 4 at addr ffff888106351d40 by task vhci_rx/69
The buggy address is located 0 bytes to the right of
allocated 320-byte region [ffff888106351c00, ffff888106351d40)
The server side (stub_rx.c) and gadget side (vudc_rx.c) already
validate number_of_packets in the CMD_SUBMIT path since commits
c6688ef9f297 ("usbip: fix stub_rx: harden CMD_SUBMIT path to handle
malicious input") and b78d830f0049 ("usbip: fix vudc_rx: harden
CMD_SUBMIT path to handle malicious input"). The server side validates
against USBIP_MAX_ISO_PACKETS because no URB exists yet at that point.
On the client side we have the original URB, so we can use the tighter
bound: the response must not exceed the original number_of_packets.
This mirrors the existing validation of actual_length against
transfer_buffer_length in usbip_recv_xbuff(), which checks the
response value against the original allocation size.
Kelvin Mbogo's series ("usb: usbip: fix integer overflow in
usbip_recv_iso()", v2) hardens the receive-side functions themselves;
this patch complements that work by catching the bad value at its
source -- in usbip_pack_ret_submit() before the overwrite -- and
using the tighter per-URB allocation bound rather than the global
USBIP_MAX_ISO_PACKETS limit.
Fix this by checking rpdu->number_of_packets against
urb->number_of_packets in usbip_pack_ret_submit() before the
overwrite. On violation, clamp to zero so that usbip_recv_iso() and
usbip_pad_iso() safely return early.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | From 6.13 (inc) to 6.18.24 (exc) |
| linux | linux_kernel | From 6.19 (inc) to 6.19.14 (exc) |
| linux | linux_kernel | From 7.0 (inc) to 7.0.1 (exc) |
| linux | linux_kernel | From 6.7 (inc) to 6.12.83 (exc) |
| linux | linux_kernel | From 2.6.39 (inc) to 6.6.136 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-787 | The product writes data past the end, or before the beginning, of the intended buffer. |
Attack-Flow Graph
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