Vulnerability details
CVE-2026-55039
Microsoft 365 Apps for EnterpriseMicrosoft ExcelMicrosoft OfficeMicrosoft Office 365 for MacMicrosoft Office LTSCMicrosoft Office LTSC for Mac
Microsoft Excel Remote Code Execution Vulnerability
CVSS 3.1
7.8High
Official description
Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 7.8High | 3.1 | CVEProject cvelistV5 (CNA) (microsoft) | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| Microsoft | Microsoft 365 Apps for Enterprise | 16.0.1 ≤ v < https://aka.ms/OfficeSecurityReleases | CVEProject cvelistV5 (CNA) |
| Microsoft | Microsoft Excel 2016 | 16.0.0.0 ≤ v < 16.0.5561.1001 | CVEProject cvelistV5 (CNA) |
| Microsoft | Microsoft Office 2019 | 19.0.0 ≤ v < https://aka.ms/OfficeSecurityReleases | CVEProject cvelistV5 (CNA) |
| Microsoft | Microsoft Office 365 for Mac | 1.0.0 ≤ v < 16.111.26071215 | CVEProject cvelistV5 (CNA) |
| Microsoft | Microsoft Office LTSC 2021 | 16.0.1 ≤ v < https://aka.ms/OfficeSecurityReleases | CVEProject cvelistV5 (CNA) |
| Microsoft | Microsoft Office LTSC 2024 | 16.0.0 ≤ v < https://aka.ms/OfficeSecurityReleases | CVEProject cvelistV5 (CNA) |
| Microsoft | Microsoft Office LTSC for Mac 2021 | 16.0.1 ≤ v < 16.111.26071215 | CVEProject cvelistV5 (CNA) |
| Microsoft | Microsoft Office LTSC for Mac 2024 | 16.0.0 ≤ v < 16.111.26071215 | CVEProject cvelistV5 (CNA) |
| Microsoft | Office Online Server | 16.0.0.0 ≤ v < 16.0.10417.20175 | CVEProject cvelistV5 (CNA) |
References and advisories
1- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55039 vendor-advisorypatch
Kolun on Telegram @kolunsec
Exploited CVEs, key news and a daily digest
Alerts for this product's next CVEsFollow the product to get new vulnerabilities on Telegram.
Details
- Published
- 2026-07-14
- Last updated
- 2026-11-01
- State
- Published
- Assigner (CNA)
- microsoft
Exploit prediction (EPSS)
0.46%
Probability of exploitation in 30 days
40.5%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- No
- Exploitation
- None
- Technical impact
- Total
Weaknesses (CWE)
- CWE-191Integer Underflow (Wrap or Wraparound)
- CWE-122Heap-based Buffer Overflow