Unity Linux 20.1050a / 20.1060a / 20.1070a Security Update: PackageKit (UTSA-2026-149761)

high Nessus Plugin ID 374280

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-2026-149761 advisory.

PackageKit is a a D-Bus abstraction layer that allows the user to manage packages in a secure way using a cross-distro, cross-architecture API. PackageKit between and including versions 1.0.2 and 1.3.4 is vulnerable to a time-of-check time-of-use (TOCTOU) race condition on transaction flags that allows unprivileged users to install packages as root and thus leads to a local privilege escalation. This is patched in version 1.3.5.

A local unprivileged user can install arbitrary RPM packages as root, including executing RPM scriptlets, without authentication. The vulnerability is a TOCTOU race condition on `transaction->cached_transaction_flags` combined with a silent state-machine guard that discards illegal backward transitions while leaving corrupted flags in place. Three bugs exist in `src/pk-transaction.c`:
1. Unconditional flag overwrite (line 4036): `InstallFiles()` writes caller-supplied flags to `transaction->cached_transaction_flags` without checking whether the transaction has already been authorized/started. A second call blindly overwrites the flags even while the transaction is RUNNING.
2. Silent state-transition rejection (lines 873882): `pk_transaction_set_state()` silently discards backward state transitions (e.g. `RUNNING` `WAITING_FOR_AUTH`) but the flag overwrite at step 1 already happened. The transaction continues running with corrupted flags.
3. Late flag read at execution time (lines 22732277): The scheduler's idle callback reads cached_transaction_flags at dispatch time, not at authorization time. If flags were overwritten between authorization and execution, the backend sees the attacker's flags.

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 PackageKit package.

Plugin Details

Severity: High

ID: 374280

File Name: unity_linux_UTSA-2026-149761.nasl

Version: 1.1

Type: Local

Family: Unity Linux Local Security Checks

Published: 10/30/2026

Updated: 10/30/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: High

Score: 8

Percentile: 99.69

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5.3

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

CVSS Score Source: CVE-2026-41651

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.9

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

Temporal Vector: CVSS:3.0/E:P/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 Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 10/30/2026

Vulnerability Publication Date: 4/22/2026

Reference Information

CVE: CVE-2026-41651

Detections

Analytics