CVE-2026-31607 (GCVE-0-2026-31607)
Vulnerability from cvelistv5 – Published: 2026-04-24 14:42 – Updated: 2026-04-27 14:04
VLAI?
Title
usbip: validate number_of_packets in usbip_pack_ret_submit()
Summary
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.
Severity ?
9.8 (Critical)
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
1325f85fa49f57df034869de430f7c302ae23109 , < 885c8591784da6314f9aa82fa460ac69f9f79e5f
(git)
Affected: 1325f85fa49f57df034869de430f7c302ae23109 , < 8d155e2d1c4102f74f82a2bf9c016164bb0f7384 (git) Affected: 1325f85fa49f57df034869de430f7c302ae23109 , < 906f16a836de13fe61f49cdce2f66f2dbd14caf4 (git) Affected: 1325f85fa49f57df034869de430f7c302ae23109 , < ef8ebb1c637b4cfb61a9dd2e013376774ee2033b (git) Affected: 1325f85fa49f57df034869de430f7c302ae23109 , < 5e1c4ece08ccdc197177631f111845a2c68eede3 (git) Affected: 1325f85fa49f57df034869de430f7c302ae23109 , < 2ab833a16a825373aad2ba7d54b572b277e95b71 (git) Affected: d9638d9236eed035a575feddec61d036dacc2676 (git) Affected: ca7d3501b7a287c18b5b470e871d3029b0f4842a (git) Affected: 1ce528277e1a66856ed3f7526c1e3458c0ed4a70 (git) Affected: db898d0c5c493ce4177d5e1d3a953e079a56a24b (git) Affected: 5aa02704b9ee67c5b2ee26d54c5f4eb99e93ba9a (git) |
|||||||
|
|||||||||
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusbip: validate number_of_packets in usbip_pack_ret_submit()\n\nWhen a USB/IP client receives a RET_SUBMIT response,\nusbip_pack_ret_submit() unconditionally overwrites\nurb-\u003enumber_of_packets from the network PDU. This value is\nsubsequently used as the loop bound in usbip_recv_iso() and\nusbip_pad_iso() to iterate over urb-\u003eiso_frame_desc[], a flexible\narray whose size was fixed at URB allocation time based on the\n*original* number_of_packets from the CMD_SUBMIT.\n\nA malicious USB/IP server can set number_of_packets in the response\nto a value larger than what was originally submitted, causing a heap\nout-of-bounds write when usbip_recv_iso() writes to\nurb-\u003eiso_frame_desc[i] beyond the allocated region.\n\nKASAN confirmed this with kernel 7.0.0-rc5:\n\n BUG: KASAN: slab-out-of-bounds in usbip_recv_iso+0x46a/0x640\n Write of size 4 at addr ffff888106351d40 by task vhci_rx/69\n\n The buggy address is located 0 bytes to the right of\n allocated 320-byte region [ffff888106351c00, ffff888106351d40)\n\nThe server side (stub_rx.c) and gadget side (vudc_rx.c) already\nvalidate number_of_packets in the CMD_SUBMIT path since commits\nc6688ef9f297 (\"usbip: fix stub_rx: harden CMD_SUBMIT path to handle\nmalicious input\") and b78d830f0049 (\"usbip: fix vudc_rx: harden\nCMD_SUBMIT path to handle malicious input\"). The server side validates\nagainst USBIP_MAX_ISO_PACKETS because no URB exists yet at that point.\nOn the client side we have the original URB, so we can use the tighter\nbound: the response must not exceed the original number_of_packets.\n\nThis mirrors the existing validation of actual_length against\ntransfer_buffer_length in usbip_recv_xbuff(), which checks the\nresponse value against the original allocation size.\n\nKelvin Mbogo\u0027s series (\"usb: usbip: fix integer overflow in\nusbip_recv_iso()\", v2) hardens the receive-side functions themselves;\nthis patch complements that work by catching the bad value at its\nsource -- in usbip_pack_ret_submit() before the overwrite -- and\nusing the tighter per-URB allocation bound rather than the global\nUSBIP_MAX_ISO_PACKETS limit.\n\nFix this by checking rpdu-\u003enumber_of_packets against\nurb-\u003enumber_of_packets in usbip_pack_ret_submit() before the\noverwrite. On violation, clamp to zero so that usbip_recv_iso() and\nusbip_pad_iso() safely return early."
}
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}
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"datePublished": "2026-04-24T14:42:29.468Z",
"dateReserved": "2026-03-09T15:48:24.122Z",
"dateUpdated": "2026-04-27T14:04:20.097Z",
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"date": "2026-05-05",
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This value is\\nsubsequently used as the loop bound in usbip_recv_iso() and\\nusbip_pad_iso() to iterate over urb-\u003eiso_frame_desc[], a flexible\\narray whose size was fixed at URB allocation time based on the\\n*original* number_of_packets from the CMD_SUBMIT.\\n\\nA malicious USB/IP server can set number_of_packets in the response\\nto a value larger than what was originally submitted, causing a heap\\nout-of-bounds write when usbip_recv_iso() writes to\\nurb-\u003eiso_frame_desc[i] beyond the allocated region.\\n\\nKASAN confirmed this with kernel 7.0.0-rc5:\\n\\n BUG: KASAN: slab-out-of-bounds in usbip_recv_iso+0x46a/0x640\\n Write of size 4 at addr ffff888106351d40 by task vhci_rx/69\\n\\n The buggy address is located 0 bytes to the right of\\n allocated 320-byte region [ffff888106351c00, ffff888106351d40)\\n\\nThe server side (stub_rx.c) and gadget side (vudc_rx.c) already\\nvalidate number_of_packets in the CMD_SUBMIT path since commits\\nc6688ef9f297 (\\\"usbip: fix stub_rx: harden CMD_SUBMIT path to handle\\nmalicious input\\\") and b78d830f0049 (\\\"usbip: fix vudc_rx: harden\\nCMD_SUBMIT path to handle malicious input\\\"). The server side validates\\nagainst USBIP_MAX_ISO_PACKETS because no URB exists yet at that point.\\nOn the client side we have the original URB, so we can use the tighter\\nbound: the response must not exceed the original number_of_packets.\\n\\nThis mirrors the existing validation of actual_length against\\ntransfer_buffer_length in usbip_recv_xbuff(), which checks the\\nresponse value against the original allocation size.\\n\\nKelvin Mbogo\u0027s series (\\\"usb: usbip: fix integer overflow in\\nusbip_recv_iso()\\\", v2) hardens the receive-side functions themselves;\\nthis patch complements that work by catching the bad value at its\\nsource -- in usbip_pack_ret_submit() before the overwrite -- and\\nusing the tighter per-URB allocation bound rather than the global\\nUSBIP_MAX_ISO_PACKETS limit.\\n\\nFix this by checking rpdu-\u003enumber_of_packets against\\nurb-\u003enumber_of_packets in usbip_pack_ret_submit() before the\\noverwrite. 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}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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