Unity Linux 20.1050a Security Update: kernel (UTSA-2026-098680)

medium Nessus Plugin ID 340471

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-2026-098680 advisory.

In the Linux kernel, the following vulnerability has been resolved:

xenbus: Use kref to track req lifetime

Marek reported seeing a NULL pointer fault in the xenbus_thread callstack:
BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace:
<TASK>
__wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0

process_msg+0x18e is req->cb(req). req->cb is set to xs_wake_up(), a thin wrapper around wake_up(), or xenbus_dev_queue_reply(). It seems like it was xs_wake_up() in this case.

It seems like req may have woken up the xs_wait_for_reply(), which kfree()ed the req. When xenbus_thread resumes, it faults on the zero-ed data.

Linux Device Drivers 2nd edition states:
Normally, a wake_up call can cause an immediate reschedule to happen, meaning that other processes might run before wake_up returns.
... which would match the behaviour observed.

Change to keeping two krefs on each request. One for the caller, and one for xenbus_thread. Each will kref_put() when finished, and the last will free it.

This use of kref matches the description in Documentation/core-api/kref.rst

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: Medium

ID: 340471

File Name: unity_linux_UTSA-2026-098680.nasl

Version: 1.1

Type: Local

Family: Unity Linux Local Security Checks

Published: 8/26/2026

Updated: 8/26/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.18

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.4

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

CVSS Score Source: CVE-2025-37949

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 4.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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: 8/10/2026

Vulnerability Publication Date: 5/20/2025

Reference Information

CVE: CVE-2025-37949

Detections

Analytics