CVE tracker / CVE-2026-55129
CVE-2026-55129
CVE-2026-55129 is the Microsoft Office Remote Code Execution Vulnerability. Microsoft rates it Critical, CVSS 7.8. It is not in CISA's Known Exploited Vulnerabilities catalog. Published July 14, 2026.
Risk summary
HighRemote Code Execution
7.8
CVSS v3 base
0.5%
EPSS: chance of exploitation in 30 days
High
Severity
Critical
Microsoft's rating
Less Likely
Microsoft: exploitation
No
In CISA KEV
Microsoft describes it: “Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.”
How to fix it
Microsoft lists 13 affected products and the update that fixes each:
- KB5002887 · fixed build 16.0.5561.1000
Microsoft Office 2016 (64-bit edition), Microsoft Office 2016 (32-bit edition) - Click to Run · fixed build https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024 for 64-bit editions, Microsoft Office LTSC 2024 for 32-bit editions, Microsoft Office LTSC 2021 for 32-bit editions, Microsoft Office LTSC 2021 for 64-bit editions, Microsoft 365 Apps for Enterprise for 64-bit Systems, and 3 more - Release Notes · fixed build 16.111.26071215
Microsoft Office 365 for Mac, Microsoft Office LTSC for Mac 2024, Microsoft Office LTSC for Mac 2021
What Microsoft changed
- July 30, 2026: Acknowledgement Updated
- July 14, 2026: Information published.
Details
- Weakness
- CWE-122: Heap-based Buffer Overflow
- Publicly disclosed (Microsoft)
- No
- Exploited (Microsoft)
- No
- Known exploited (CISA KEV)
- Not listed
- Published
- July 14, 2026
- Last revised
- July 30, 2026
Get told when this changes
Senserva Watch emails Microsoft security and patch alerts when something moves: a new exploitation report, a revised fix, a known issue. Free, one email address.
References
From Microsoft, CISA, NVD and FIRST data; the Microsoft details were read when this page was opened. Check the references above before you act.