Detections
Analytics

Security Updates for Microsoft Office Online Server (January 2026)

high Nessus Plugin ID 283462

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Synopsis

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

Description

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

 - Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
 (CVE-2026-20950)

 - Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to execute code locally. (CVE-2026-20955)

 - Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to execute code locally. (CVE-2026-20957)

Solution

Microsoft has released 5002824 to address this issue.

See Also

https://support.microsoft.com/en-us/help/5002824

Plugin Details

Severity: High

ID: 283462

File Name: smb_nt_ms26_jan_office_web.nasl

Version: 1.1

Type: local

Agent: windows

Published: 1/13/2026

Updated: 1/13/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

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: 1/13/2026

Vulnerability Publication Date: 1/13/2026

Reference Information

CVE: CVE-2026-20950, CVE-2026-20955, CVE-2026-20957

MSFT: MS25-5002824

MSKB: 5002824