Microsoft Security Update Guide · Office / Microsoft 365 Apps
Microsoft Office Excel Information Disclosure Vulnerability
Published
What does this mean?
- Information Disclosure. An attacker can see information that is not meant for them.
- 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 365 Apps for Enterprise for 64-bit Systems: KBRelease Notes
https://aka.ms/OfficeSecurityReleases - Microsoft Office LTSC 2024 for 64-bit editions: KBRelease Notes
16.0.17932.21056 - Microsoft Office LTSC 2021 for 64-bit editions: KBRelease Notes
16.0.14334.20974 - Microsoft Office LTSC 2021 for 32-bit editions: KBRelease Notes
16.0.14334.20974 - Microsoft Office LTSC 2024 for 32-bit editions: KBRelease Notes
16.0.17932.21056 - Microsoft 365 Apps for Enterprise for 32-bit Systems: KBRelease Notes
https://aka.ms/OfficeSecurityReleases
- Microsoft 365 Apps for Enterprise for 64-bit Systems: KBRelease Notes
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
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
13 okt 2026
Impact
Information Disclosure
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 Unlikely
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 365 Apps for Enterprise for 64-bit Systems | KBRelease Notes | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC 2024 for 64-bit editions | KBRelease Notes | 16.0.17932.21056 |
| Microsoft Office LTSC 2021 for 64-bit editions | KBRelease Notes | 16.0.14334.20974 |
| Microsoft Office LTSC 2021 for 32-bit editions | KBRelease Notes | 16.0.14334.20974 |
| Microsoft Office LTSC 2024 for 32-bit editions | KBRelease Notes | 16.0.17932.21056 |
| Microsoft 365 Apps for Enterprise for 32-bit Systems | KBRelease Notes | https://aka.ms/OfficeSecurityReleases |
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.
- Is the Preview Pane an attack vector for this vulnerability?
- No, the Preview Pane is not an attack vector.
Revisions
| Version | Date | Note |
|---|---|---|
| 1 | 13 okt 2026 | Information published. |
This is in the weekly digest for week 42: everything that changed in Microsoft 365 this week. →
View at Microsoft → ← All security advisories
Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
