Unity Linux 20.1050e Security Update: kernel (UTSA-2026-102054)

high Nessus Plugin ID 338575

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-2026-102054 advisory.

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

dm-thin: fix metadata refcount underflow

There's a bug in dm-thin in the function rebalance_children. If the internal btree node has one entry, the code tries to copy all btree entries from the node's child to the node itself and then decrement the child's reference count.

If the child node is shared (it has reference count > 1), we won't free it, so there would be two pointers to each of the grandchildren nodes.
But the reference counts of the grandchildren is not increased, thus the reference count doesn't match the number of pointers that point to the grandchildren. This results in device mapper: space map common: unable to decrement block errors.

Fix this bug by incrementing reference counts on the grandchildren if the btree node is shared.

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: 338575

File Name: unity_linux_UTSA-2026-102054.nasl

Version: 1.1

Type: Local

Family: Unity Linux Local Security Checks

Published: 8/21/2026

Updated: 8/21/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 57.95

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

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

CVSS Score Source: CVE-2026-46107

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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: 8/17/2026

Vulnerability Publication Date: 5/28/2026

Reference Information

CVE: CVE-2026-46107

Detections

Analytics