CVE-2026-65807: Microsoft Excel Remote Code Execution Vulnerability
CVE-2026-65807 is a remote code execution vulnerability in Microsoft Excel, rated Important by Microsoft, with a CVSS 3.1 base score of 8.8 (High). An attacker can exploit it remotely over the network, without any privileges and only if a user takes an action. Microsoft has not reported exploitation in the wild and rates exploitation as less likely. The EPSS model estimates a 0.82% probability of exploitation activity in the next 30 days, higher than 57% of all scored vulnerabilities. Microsoft released the fix on 11 August 2026 in the August 2026 Patch Tuesday, delivered through 2 security updates (KB5002884, KB5002903). It affects 14 products in 1 product family (Microsoft Office).
Key facts
- CVE ID
- CVE-2026-65807
- Severity
- High CVSS 8.8
- Microsoft severity
- Important
- Impact
- Remote Code Execution
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- Less Likely
- Weakness
- CWE-843
- EPSS
- 0.82% (percentile 57%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- August 2026 Patch Tuesday
- Product families
- Microsoft Office
CVSS score and vector
Microsoft scores CVE-2026-65807 at 8.8 (temporal 7.7) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | Required |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | High |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Description
Access of resource using incompatible type ('type confusion') in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
Frequently asked questions (Microsoft)
According to the CVSS metric, the attack vector is network (AV:N) and user interaction is required (UI:R). What is the target context of the remote code execution?
This attack requires a user to open a specially crafted file from the attacker to initiate remote code execution.
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.
Affected products (14)
Microsoft Office
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Microsoft Office 365 for Mac | Release Notes | Security Update | 16.112.26081010 | Maybe |
| Office Online Server | KB5002884 | Security Update | 16.0.10417.20175 | Maybe |
| Microsoft Office 2019 for 32-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office 2019 for 64-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft 365 Apps for Enterprise for 32-bit Systems | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft 365 Apps for Enterprise for 64-bit Systems | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC for Mac 2021 | Release Notes | Security Update | 16.112.26081010 | Maybe |
| Microsoft Office LTSC 2021 for 64-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC 2021 for 32-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC 2024 for 32-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC 2024 for 64-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC for Mac 2024 | Release Notes | Security Update | 16.112.26081010 | Maybe |
| Microsoft Excel 2016 (32-bit edition) | KB5002903 | Security Update | 16.0.5565.1001 | Maybe |
| Microsoft Excel 2016 (64-bit edition) | KB5002903 | Security Update | 16.0.5565.1001 | Maybe |
Security updates (2)
NIST NVD data
- NVD status
- Analyzed
- NVD CVSS
- 8.8 (HIGH)
- NVD weakness
- CWE-843
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| 365 apps (x64) | all listed versions |
| 365 apps (x86) | all listed versions |
| excel 2016 (x64) | all listed versions |
| excel 2016 (x86) | all listed versions |
| microsoft 365 | all listed versions |
| office 2019 (x64) | all listed versions |
| office 2019 (x86) | all listed versions |
| office 2021 (x64) | all listed versions |
| office 2021 (x86) | all listed versions |
| office 2021 | all listed versions |
| office 2024 (x64) | all listed versions |
| office 2024 (x86) | all listed versions |
| office 2024 | all listed versions |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65807 (Vendor Advisory, Patch)
Acknowledgments
- Anonymous
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |