Unity Linux 20.1070a Security Update: kernel (UTSA-2026-143115)

high Nessus Plugin ID 370800

Synopsis

The Unity Linux host is missing one or more security updates.

Description

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-143115 advisory.

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.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the affected kernel package.

Plugin Details

Severity: High

ID: 370800

File Name: unity_linux_UTSA-2026-143115.nasl

Version: 1.1

Type: Local

Family: Unity Linux Local Security Checks

Published: 10/22/2026

Updated: 10/22/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.5

Percentile: 96.89

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-31607

CVSS v3

Risk Factor: High

Base Score: 7.3

Temporal Score: 6.4

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/UOS-Server/release, Host/UOS-Server/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 10/23/2026

Vulnerability Publication Date: 4/24/2026

Reference Information

CVE: CVE-2026-31607

Detections

Analytics