CVE-2026-55039: CWE-191: Integer Underflow (Wrap or Wraparound) in Microsoft Microsoft 365 Apps for Enterprise
Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AI Analysis
Technical Summary
CVE-2026-55039 is a CWE-191 integer underflow vulnerability in Microsoft Office Excel as part of Microsoft 365 Apps for Enterprise. This vulnerability can lead to local code execution by an unauthorized attacker. The CVSS v3.1 base score is 7.8, indicating high severity with impacts on confidentiality, integrity, and availability. The vulnerability affects version 16.0.1 of the product. Microsoft has released an official fix and manages remediation for this cloud-hosted service. No known exploits are reported in the wild at this time.
Potential Impact
Successful exploitation of this integer underflow vulnerability could allow an unauthorized attacker to execute code locally on the affected system, potentially leading to full compromise of confidentiality, integrity, and availability of the affected environment.
Mitigation Recommendations
An official fix is available from Microsoft. Since Microsoft 365 Apps for Enterprise is a cloud service, Microsoft manages the remediation server-side. Users and administrators should ensure their installations are updated according to Microsoft's guidance available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55039.
CVE-2026-55039: CWE-191: Integer Underflow (Wrap or Wraparound) in Microsoft Microsoft 365 Apps for Enterprise
Description
Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
CVSS v3.1
Score 7.8high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-55039 is a CWE-191 integer underflow vulnerability in Microsoft Office Excel as part of Microsoft 365 Apps for Enterprise. This vulnerability can lead to local code execution by an unauthorized attacker. The CVSS v3.1 base score is 7.8, indicating high severity with impacts on confidentiality, integrity, and availability. The vulnerability affects version 16.0.1 of the product. Microsoft has released an official fix and manages remediation for this cloud-hosted service. No known exploits are reported in the wild at this time.
Potential Impact
Successful exploitation of this integer underflow vulnerability could allow an unauthorized attacker to execute code locally on the affected system, potentially leading to full compromise of confidentiality, integrity, and availability of the affected environment.
Mitigation Recommendations
An official fix is available from Microsoft. Since Microsoft 365 Apps for Enterprise is a cloud service, Microsoft manages the remediation server-side. Users and administrators should ensure their installations are updated according to Microsoft's guidance available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55039.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2026-06-16T14:13:49.835Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Is Cloud Service
- true
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55039","vendor":"Microsoft"}]
Threat ID: 6a5676b168715ace43f0992e
Added to database: 07/14/2026, 17:49:37 UTC
Last enriched: 07/14/2026, 19:33:17 UTC
Last updated: 07/15/2026, 01:47:29 UTC
Views: 2
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.