Detections
Analytics

Security Updates for Microsoft Office Online Server (May 2026)

high Nessus Plugin ID 314339

Synopsis

The Microsoft Office Online Server or Office Web Apps installation on the remote host is affected by multiple vulnerabilities.

Description

The Microsoft Office Online Server or Office Web Apps installation on the remote host is missing security updates. It is, therefore, affected by multiple vulnerabilities:

 - Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
 (CVE-2026-40359)

 - Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally. (CVE-2026-40360)

 - Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally. (CVE-2026-40362)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Apply Security Update 5002871

See Also

https://support.microsoft.com/help/5002871

Plugin Details

Severity: High

ID: 314339

File Name: smb_nt_ms26_may_office_web.nasl

Version: 1.1

Type: Local

Agent: windows

Published: 5/12/2026

Updated: 5/12/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

CVSS v2

Risk Factor: High

Base Score: 9.3

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

CVSS Score Source: CVE-2026-40359

CVSS v3

Risk Factor: High

Base Score: 7.8

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

Vulnerability Information

CPE: cpe:/a:microsoft:office_online_server, cpe:/a:microsoft:office_web_apps

Required KB Items: SMB/MS_Bulletin_Checks/Possible

Patch Publication Date: 5/12/2026

Vulnerability Publication Date: 5/12/2026

Reference Information

CVE: CVE-2026-40359, CVE-2026-40360, CVE-2026-40362

MSFT: MS26-5002871

MSKB: 5002871