Unity Linux 20.1050e Security Update: kernel (UTSA-2026-101976)

medium Nessus Plugin ID 337281

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-2026-101976 advisory.

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

ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1

When allocating initialized blocks from a large unwritten extent, or when splitting an unwritten extent during end I/O and converting it to initialized, there is currently a potential issue of stale data if the extent needs to be split in the middle.

0 A B N [UUUUUUUUUUUU] U: unwritten extent [--DDDDDDDD--] D: valid data |<- ->| ----> this range needs to be initialized

ext4_split_extent() first try to split this extent at B with EXT4_EXT_DATA_ENTIRE_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but ext4_split_extent_at() failed to split this extent due to temporary lack of space. It zeroout B to N and mark the entire extent from 0 to N as written.

0 A B N [WWWWWWWWWWWW] W: written extent [SSDDDDDDDDZZ] Z: zeroed, S: stale data

ext4_split_extent() then try to split this extent at A with EXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and left a stale written extent from 0 to A.

0 A B N [WW|WWWWWWWWWW] [SS|DDDDDDDDZZ]

Fix this by pass EXT4_EXT_DATA_PARTIAL_VALID1 to ext4_split_extent_at() when splitting at B, don't convert the entire extent to written and left it as unwritten after zeroing out B to N. The remaining work is just like the standard two-part split. ext4_split_extent() will pass the EXT4_EXT_DATA_VALID2 flag when it calls ext4_split_extent_at() for the second time, allowing it to properly handle the split. If the split is successful, it will keep extent from 0 to A as unwritten.

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: 337281

File Name: unity_linux_UTSA-2026-101976.nasl

Version: 1.1

Type: Local

Family: Unity Linux Local Security Checks

Published: 8/18/2026

Updated: 8/18/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.75

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-2026-45858

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: 8/17/2026

Vulnerability Publication Date: 3/27/2026

Reference Information

CVE: CVE-2026-45858

Detections

Analytics