Unity Linux 20.1050e Security Update: kernel (UTSA-2026-007548)

medium Nessus Plugin ID 307072

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-2026-007548 advisory.

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

posix-timers: Ensure timer ID search-loop limit is valid

posix_timer_add() tries to allocate a posix timer ID by starting from the cached ID which was stored by the last successful allocation.

This is done in a loop searching the ID space for a free slot one by one. The loop has to terminate when the search wrapped around to the starting point.

But that's racy vs. establishing the starting point. That is read out lockless, which leads to the following problem:

CPU0 CPU1 posix_timer_add() start = sig->posix_timer_id;
lock(hash_lock);
... posix_timer_add() if (++sig->posix_timer_id < 0) start = sig->posix_timer_id;
sig->posix_timer_id = 0;

So CPU1 can observe a negative start value, i.e. -1, and the loop break never happens because the condition can never be true:

if (sig->posix_timer_id == start) break;

While this is unlikely to ever turn into an endless loop as the ID space is huge (INT_MAX), the racy read of the start value caught the attention of KCSAN and Dmitry unearthed that incorrectness.

Rewrite it so that all id operations are under the hash lock.

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: 307072

File Name: unity_linux_UTSA-2026-007548.nasl

Version: 1.1

Type: Local

Family: Unity Linux Local Security Checks

Published: 4/17/2026

Updated: 4/17/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.6

CVSS v2

Risk Factor: Medium

Base Score: 4.5

Temporal Score: 3.3

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

CVSS Score Source: CVE-2023-53728

CVSS v3

Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.6

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:N/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: 4/17/2026

Vulnerability Publication Date: 7/21/2021

Reference Information

CVE: CVE-2023-53728

Detections

Analytics