Microsoft Security Update Guide · Office / Microsoft 365 Apps
Microsoft Office Information Disclosure Vulnerability
Published · updated 19 jun 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 3.3 out of 10: low. 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 2016 (64-bit edition): KB5002878
16.0.5556.1005 - Microsoft Office 2016 (32-bit edition): KB5002878
16.0.5556.1005 - Microsoft Office LTSC for Mac 2024: KBRelease Notes
16.110.26061317 - 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: KB5002873
16.0.19725.20384
- Microsoft Office 2016 (64-bit edition): KB5002878
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
9 jun 2026
Last revised
19 jun 2026 (v2)
Impact
Information Disclosure
Max severity
Important
Weakness
CVSS 3.1
3.3 / 2.9 (base / temporal)
Vector string
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/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 | Local |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | Required |
| Scope | Unchanged |
| Confidentiality | Low |
| 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 2016 (64-bit edition) | KB5002878 · Security Update | 16.0.5556.1005 |
| Microsoft Office 2016 (32-bit edition) | KB5002878 · Security Update | 16.0.5556.1005 |
| Microsoft Office LTSC for Mac 2024 | KBRelease Notes · Security Update | 16.110.26061317 |
| 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 | KB5002873 · Security Update | 16.0.19725.20384 |
| 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 |
| Microsoft Office LTSC for Mac 2021 | KBRelease Notes · Security Update | 16.110.26061317 |
| 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 | KB5002874 · Security Update | 16.0.10417.20153 |
| Microsoft SharePoint Server 2019 | KB5002876 · Security Update | 16.0.10417.20153 |
| Microsoft SharePoint Enterprise Server 2016 | KB5002880 · Security Update | 16.0.5556.1005 |
| Microsoft SharePoint Enterprise Server 2016 | KB5002881 · Security Update | 16.0.5556.1002 |
| Microsoft Office 365 for Mac | KBRelease Notes · Security Update | 16.110.26061317 |
FAQ
- 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 metrics, successful exploitation of this vulnerability could lead to some loss of confidentiality (C:L),but lead to no loss of availability (A:N) and integrity (I:N)? What does that mean for this vulnerability?
- An attacker who successfully exploited the vulnerability could view some sensitive information (Confidentiality) but not all resources within the impacted component may be divulged to the attacker. The attacker cannot make changes to disclosed information (Integrity) or limit access to the resource (Availability).
- Is the Preview Pane an attack vector for this vulnerability?
- No, the Preview Pane is not an attack vector.
- 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.
- Are the updates for Microsoft Office LTSC for Mac 2021 and 2024 currently available?
- Yes. As of June 16, 2025, the security update for Microsoft Office LTSC for Mac 2021, 2024 and Microsoft Office 365 for Mac are available. Customers running Microsoft Office LTSC for Mac 2021, 2024 and Microsoft Office 365 for Mac should ensure the update is installed to be protected from this vulnerability.
Revisions
| Version | Date | Note |
|---|---|---|
| 2 | 19 jun 2026 | Microsoft is announcing the availability of the security updates for Microsoft Office for Mac. Customers running affected Mac software should install the update for their product to be protected from this vulnerability. Customers running other Microsoft Office software do not need to take any action. See the Release Notes for more information and download links. |
| 1 | 9 jun 2026 | Information published. |
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Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
