Microsoft Security Update Guide · Office / Microsoft 365 Apps
Microsoft Excel 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 with access to the device itself, without an account and if a user takes part, for example by opening a link or file.
- CVSS 7.8 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 365 for Mac: KBRelease Notes
16.111.26071215 - Microsoft Excel 2016 (64-bit edition): KB5002886
16.0.5561.1001 - Microsoft Excel 2016 (32-bit edition): KB5002886
16.0.5561.1001 - Microsoft Office LTSC for Mac 2024: KBRelease Notes
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 Office 365 for Mac: KBRelease Notes
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
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
14 jul 2026
Impact
Remote Code Execution
Max severity
Important
Weakness
CVSS 3.1
7.8 / 6.8 (base / temporal)
Vector string
CVSS:3.1/AV:L/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 | Local |
| 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 365 for Mac | KBRelease Notes · Security Update | 16.111.26071215 |
| Microsoft Excel 2016 (64-bit edition) | KB5002886 · Security Update | 16.0.5561.1001 |
| Microsoft Excel 2016 (32-bit edition) | KB5002886 · Security Update | 16.0.5561.1001 |
| 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 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 | 16.111.26071215 |
| 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 |
| Office Online Server | KB5002884 · Security Update | 16.0.10417.20175 |
FAQ
- According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is a remote code execution?
- The word Remote in the title refers to the location of the attacker. This type of exploit is sometimes referred to as Arbitrary Code Execution (ACE). The attack itself is carried out locally. This means an attacker or victim needs to execute code from the local machine to exploit the vulnerability.
- 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 | 14 jul 2026 | Information published. |
What changed in Microsoft 365 this week? →
View at Microsoft → ← All security advisories
Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
