Microsoft Security Update Guide · Office / Microsoft 365 Apps
Microsoft Office Spoofing Vulnerability
Published
What does this mean?
- Spoofing. An attacker can pretend to be another user or source, for example through a misleading link or page.
- 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 6.5 out of 10: medium. 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 2024 for 32-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 Office 2016 (32-bit edition): KB5002916
16.0.5569.1003 - Microsoft Office 2016 (64-bit edition): KB5002916
16.0.5569.1003 - Microsoft Office LTSC 2024 for 64-bit editions: KBRelease Notes
16.0.17932.20960 - Microsoft Office LTSC 2021 for 64-bit editions: KBClick to Run
https://aka.ms/OfficeSecurityReleases
- Microsoft Office LTSC 2024 for 32-bit editions: KBClick to Run
Insufficiently protected credentials in Microsoft Office allows an unauthorized attacker to perform spoofing over a network.
Key facts
Released
8 sep 2026
Impact
Spoofing
Max severity
Important
Weakness
CVSS 3.1
6.5 / 5.7 (base / temporal)
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/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 | None |
| Availability | None |
| Temporal score metrics | |
| Exploit Code Maturity | Unproven |
| Remediation Level | Official Fix |
| Report Confidence | Confirmed |
Affected products and updates
| Product | Update | Build |
|---|---|---|
| Microsoft Office LTSC 2024 for 32-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 Office 2016 (32-bit edition) | KB5002916 | 16.0.5569.1003 |
| Microsoft Office 2016 (64-bit edition) | KB5002916 | 16.0.5569.1003 |
| Microsoft Office LTSC 2024 for 64-bit editions | KBRelease Notes | 16.0.17932.20960 |
| Microsoft Office LTSC 2021 for 64-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 365 Apps for Enterprise for 32-bit Systems | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office 2019 for 64-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office 2019 for 32-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
FAQ
- According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do?
- A user interacting with the file in multiple ways will cause the NTLM hash to be leaked. A few interactions which trigger this leak include: Opening the parent folder in Explorer Clicking the file (any mouse button) Dragging the file Deleting the file
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.
