Microsoft Security Update Guide · Office / Microsoft 365 Apps
Microsoft Office Information Disclosure Vulnerability
Published · updated 17 sep 2026
What does this mean?
- Information Disclosure. An attacker can see information that is not meant for them.
- It can be exploited with access to the device itself, without an account and if a user takes part, for example by opening a link or file.
- CVSS 5.5 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 for Mac 2021: KBRelease Notes
16.111.26071215 - 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 - Microsoft SharePoint Server 2019: KB5002883
16.0.10417.20175
- Microsoft Office LTSC for Mac 2021: KBRelease Notes
Out-of-bounds read in Microsoft Office allows an unauthorized attacker to disclose information locally.
How do I check if I am affected?
SharePoint Server: check and update
- Check your farm build in the SharePoint Management Shell:
Or in Central Administration → Upgrade and Migration → Check product and patch installation status.(Get-SPFarm).BuildVersion - If the build is equal to or higher than the build under "Affected products and updates" below, this vulnerability is fixed. A later cumulative update includes the fix too.
- Otherwise install the update on every server in the farm, then run the SharePoint Products Configuration Wizard, or:
PSConfig.exe -cmd upgrade -inplace b2b -wait -cmd applicationcontent -install -cmd installfeatures -cmd secureresources -cmd services -install - You do not need to update SharePoint Online in Microsoft 365; Microsoft does that.
What kind of flaw is this?
- CWE-125: Out-of-bounds Read
The program reads outside its allocated memory and can leak information.
Key facts
Released
14 jul 2026
Last revised
17 sep 2026 (v1.2)
Impact
Information Disclosure
Max severity
Important
Weakness
CVSS 3.1
5.5 / 4.8 (base / temporal)
Vector string
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H/E:U/RL:O/RC:CPublicly disclosed
No
Exploited
No
Exploitability assessment
Exploitation Unlikely
Customer action required
Yes
Links
CVSS metrics
| Base score metrics | |
|---|---|
| Attack Vector | Local |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | Required |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity | None |
| 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 for Mac 2021 | KBRelease Notes · Security Update | 16.111.26071215 |
| 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 |
| Microsoft SharePoint Server 2019 | KB5002883 · Security Update | 16.0.10417.20175 |
| Microsoft SharePoint Server 2019 | KB5002885 · Security Update | 16.0.10417.20175 |
| Microsoft SharePoint Enterprise Server 2016 | KB5002891 · Security Update | 16.0.5561.1001 |
| Microsoft SharePoint Enterprise Server 2016 | KB5002892 · Security Update | 16.0.5561.1001 |
| Microsoft Office 365 for Mac | KBRelease Notes · Security Update | 16.111.26071215 |
| Microsoft Office 2016 (64-bit edition) | KB5002887 · Security Update | 16.0.5561.1000 |
| Microsoft Office 2016 (32-bit edition) | KB5002887 · Security Update | 16.0.5561.1000 |
| Microsoft Office LTSC for Mac 2024 | KBRelease Notes · Security Update | 16.111.26071215 |
| Microsoft Office LTSC 2024 for 64-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC 2024 for 32-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft SharePoint Server Subscription Edition | KB5002882 · Security Update | 16.0.19725.20434 |
| Microsoft Office LTSC 2021 for 32-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC 2021 for 64-bit editions | KBClick to Run | https://aka.ms/OfficeSecurityReleases |
FAQ
- According to the CVSS metrics, successful exploitation of this vulnerability could lead to some loss of confidentiality (C:L), no loss to integrity (I:N) and lead to some loss of availability (A:L). What is the impact of this vulnerability?
- Successful exploitation of this vulnerability could allow an attacker to access limited sensitive information from system memory and may cause intermittent interruptions or reduced performance in the affected application. However, it would not allow the attacker to modify data.
- What type of information could be disclosed by this vulnerability?
- An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory.
- According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do?
- An attacker must send a user a malicious Office file and convince them to open it.
- Is the Preview Pane an attack vector for this vulnerability?
- No, the Preview Pane is not an attack vector.
Revisions
| Version | Date | Note |
|---|---|---|
| 1.2 | 17 sep 2026 | Updated an acknowledgement. This is an informational change only. |
| 1.1 | 15 sep 2026 | Updated an acknowledgement. This is an informational change only. |
| 1 | 14 jul 2026 | Information published. |
This is in the weekly digest for week 38 · What changed this week? →
View at Microsoft → ← All security advisories
Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
