Microsoft Security Update Guide · Office / Microsoft 365 Apps
Microsoft Office Word Remote Code Execution Vulnerability
Published
What does this mean?
- Remote Code Execution. An attacker can run their own code on the system remotely. This is the most serious type: it can lead to taking over the system.
- It can be exploited over the network (including from the internet if the service is reachable there), without an account and if a user takes part, for example by opening a link or file.
- CVSS 8.8 out of 10: high. Microsoft rates it Important.
- No attacks reported; Microsoft expects exploitation to be less likely.
- What should you do? Install the security update for the version you run (or a later cumulative update):
- Microsoft Office LTSC 2021 for 64-bit editions: KBClick to Run
https://aka.ms/OfficeSecurityReleases - Microsoft Office LTSC 2021 for 32-bit editions: KBClick to Run
https://aka.ms/OfficeSecurityReleases - Microsoft Word 2016 (64-bit edition): KB5002923
16.0.5569.1002 - Microsoft Office 365 for Mac
- Microsoft Word 2016 (32-bit edition): KB5002923
16.0.5569.1002 - Microsoft Office LTSC for Mac 2024
- Microsoft Office LTSC 2021 for 64-bit editions: KBClick to Run
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.
How do I check if I am affected?
Update the app
- Update the app through the App Store, Google Play or the app's own automatic updates.
- If you manage devices with Intune, check in the Intune admin center which devices still run an older version.
What kind of flaw is this?
- CWE-122: Heap-based Buffer Overflow
A heap buffer overflows, which can lead to running code.
Key facts
Released
8 sep 2026
Impact
Remote Code Execution
Max severity
Important
Weakness
CVSS 3.1
8.8 / 7.7 (base / temporal)
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:CPublicly disclosed
No
Exploited
No
Exploitability assessment
Exploitation Less Likely
Customer action required
Yes
Links
CVSS metrics
| Base score metrics | |
|---|---|
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | Required |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity | High |
| Availability | High |
| Temporal score metrics | |
| Exploit Code Maturity | Unproven |
| Remediation Level | Official Fix |
| Report Confidence | Confirmed |
Affected products and updates
| Product | Update | Build |
|---|---|---|
| Microsoft Office LTSC 2021 for 64-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC 2021 for 32-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Word 2016 (64-bit edition) | KB5002923 · Security Update | 16.0.5569.1002 |
| Microsoft Office 365 for Mac | — | — |
| Microsoft Word 2016 (32-bit edition) | KB5002923 · Security Update | 16.0.5569.1002 |
| Microsoft Office LTSC for Mac 2024 | — | — |
| Microsoft Office LTSC 2024 for 64-bit editions | KBRelease Notes | 16.0.17932.20960 |
| Microsoft Office LTSC 2024 for 32-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft 365 Apps for Enterprise for 64-bit Systems | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC for Mac 2021 | — | — |
| Microsoft 365 Apps for Enterprise for 32-bit Systems | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office 2019 for 32-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office 2019 for 64-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
FAQ
- How could an attacker exploit this vulnerability?
- An attacker could convince a user to open a specially crafted document and interact with it in an affected application. Successful exploitation could allow the attacker to execute code on the affected system.
Revisions
| Version | Date | Note |
|---|---|---|
| 1 | 8 sep 2026 | Information published. |
This is in the weekly digest for week 37 · What changed this week? →
View at Microsoft → ← All security advisories
Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
