Microsoft Security Update Guide · Office / Microsoft 365 Apps
Microsoft Excel Security Feature Bypass Vulnerability
Published · updated 19 jun 2026
What does this mean?
- Security Feature Bypass. An attacker can get around a security feature.
- 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 365 for Mac: KBRelease Notes
16.110.26061317 - 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 Office LTSC for Mac 2021: KBRelease Notes
16.110.26061317 - Microsoft 365 Apps for Enterprise for 64-bit Systems: KBClick to Run
https://aka.ms/OfficeSecurityReleases
- Microsoft Office 365 for Mac: KBRelease Notes
Protection mechanism failure in Microsoft Office Excel allows an unauthorized attacker to bypass a security feature 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.
Key facts
Released
9 jun 2026
Last revised
19 jun 2026 (v2)
Impact
Security Feature Bypass
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 365 for Mac | KBRelease Notes · Security Update | 16.110.26061317 |
| 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 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 |
FAQ
- 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).
- 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.
- What kind of security feature could be bypassed by successfully exploiting this vulnerability?
- Successful exploitation of this vulnerability would allow an attacker to bypass the Office Protected View and open in editing mode rather than protected mode.
- Is the Preview Pane an attack vector for this vulnerability?
- No, the Preview Pane is not an attack vector.
- 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. |
What changed in Microsoft 365 this week? →
View at Microsoft → ← All security advisories
Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
