CVE-2026-45458: Microsoft Outlook and Word Remote Code Execution Vulnerability

Overview

Severity
High (CVSS 8.4)
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Remote Code Execution
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2026-Jun
Released
2026-06-09

Description

Access of resource using incompatible type ('type confusion') in Microsoft Office allows an unauthorized attacker to execute code locally.

FAQ

According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is a remote code execution? The word Remote in the title refers to the location of the attacker. This type of exploit is sometimes referred to as Arbitrary Code Execution (ACE). The attack itself is carried out locally. This means an attacker or victim needs to execute code from the local machine to exploit the vulnerability. There are multiple update packages available for some of the affected software. Do I need to install all the updates listed in the Security Updates table for the software? Yes. Customers should apply all updates offered for the software installed on their systems. If multiple updates apply, they can be installed in any order. Why is Microsoft Word listed in the Security Updates table but the title indicates that Outlook is affected? This vulnerability can be exploited when rendering email in Outlook (classic). The rendering of email in Outlook (classic) uses Microsoft Word functionality. The vulnerability is in the Word functionality and is exploitable through Outlook (classic). Are the updates for the Microsoft Office LTSC and Microsoft 365 for Mac currently available? The security update for Microsoft Office LTSC for Mac 2021, 2024 and Microsoft 365 for Mac are not immediately available. The updates will be released as soon as possible, and when they are available, customers will be notified via a revision to this CVE information. Is the Preview Pane an attack vector for this vulnerability? Yes, the Preview Pane is an attack vector.

Affected Products (16)

Microsoft Office

  • Microsoft Office 365 for Mac
  • Microsoft SharePoint Enterprise Server 2016
  • Microsoft SharePoint Server 2019
  • Microsoft Office 2019 for 32-bit editions
  • Microsoft Office 2019 for 64-bit editions
  • Microsoft 365 Apps for Enterprise for 32-bit Systems
  • Microsoft 365 Apps for Enterprise for 64-bit Systems
  • Microsoft Office LTSC for Mac 2021
  • Microsoft Office LTSC 2021 for 64-bit editions
  • Microsoft Office LTSC 2021 for 32-bit editions
  • Microsoft SharePoint Server Subscription Edition
  • Microsoft Office LTSC 2024 for 32-bit editions
  • Microsoft Office LTSC 2024 for 64-bit editions
  • Microsoft Office LTSC for Mac 2024
  • Microsoft Word 2016 (32-bit edition)
  • Microsoft Word 2016 (64-bit edition)

Security Updates (6)

Acknowledgments

Jonghoi Kim, Donghyun Oh with kloy

Revision History

  • 2026-06-09: Information published.