Unity Linux 20.1050e Security Update: kernel (UTSA-2026-099704)

high Nessus Plugin ID 336491

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-2026-099704 advisory.

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

NFSv4: include MAY_WRITE in open permission mask for O_TRUNC

POSIX requires write permission to truncate a file, so an open() that specifies O_TRUNC must be authorized for write access regardless of the O_ACCMODE access mode.

nfs_open_permission_mask() builds the access mask passed to nfs_may_open(), which is the local authorization gate for OPENs the client serves itself from a cached write delegation via the can_open_delegated() path in nfs4_try_open_cached(). The mask is derived from O_ACCMODE alone, so an open(O_RDONLY | O_TRUNC) against a file the caller cannot write requests only MAY_READ and passes the local check. The OPEN is then satisfied locally and the truncation is issued to the server as a SETATTR(size=0) over the delegation stateid, which the server accepts under standard write-delegation semantics.
POSIX requires that this open fail with EACCES.

Include MAY_WRITE in the mask whenever O_TRUNC is set so the local check matches the access the server would have enforced.

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: 336491

File Name: unity_linux_UTSA-2026-099704.nasl

Version: 1.1

Type: Local

Family: Unity Linux Local Security Checks

Published: 8/17/2026

Updated: 8/17/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.3

Percentile: 53.6

CVSS v2

Risk Factor: Medium

Base Score: 6.2

Temporal Score: 4.6

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

CVSS Score Source: CVE-2026-64298

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.2

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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: 8/13/2026

Vulnerability Publication Date: 7/23/2026

Reference Information

CVE: CVE-2026-64298

Detections

Analytics