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Privacy Statement Third-Party Cookies Accept Reject Manage cookies MSRC  Customer Guidance  Security Update Guide  Vulnerabilities  CVE-2026-40360 Microsoft Excel Information Disclosure Vulnerability New On this page  CVE-2026-40360  Subscribe RSS PowerShell  API  CSAF Security Vulnerability Released: May 12, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-40360  Impact Information Disclosure Max Severity Important Weakness CWE-125: Out-of-bounds Read CVSS Source Microsoft Vector String 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 Metrics CVSS:3.1 7.8 / 6.8  Base score metrics: 7.8 / Temporal score metrics: 6.8  Expand all  Collapse all Metric Value   Base score metrics(8) Attack Vector Local Attack Complexity Low Privileges Required None User Interaction Required Scope Unchanged Confidentiality High Integrity High Availability High   Temporal score metrics(3) Exploit Code Maturity Unproven Remediation Level Official Fix Report Confidence Confirmed Please see Common Vulnerability Scoring System for more information on the definition of these metrics. Executive Summary Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally. Exploitability The following table provides an exploitability assessment for this vulnerability at the time of original publication. Publicly disclosed No Exploited No Exploitability assessment Exploitation Unlikely FAQ What type of information could be disclosed by this vulnerability? An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory. 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. Is the Preview Pane an attack vector for this vulnerability? No, the Preview Pane is not an attack vector. Acknowledgements f4 & Zhiniang Peng with HUST 𝕏 @ dnpushme Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgements for more information. Security Updates To determine the support lifecycle for your software, see the Microsoft Support Lifecycle. Release date Descending  Edit columns  Download  Filters  Product Family  Max Severity  Impact  Platform   Clear Release date  Product Platform Impact Max Severity Article Download Build Number Assigning CNA Customer Action Required Title: Release date, Content: May 12, 2026 Microsoft Excel 2016 (64-bit edition) - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Excel 2016 (64-bit edition), Content:, 1 link 5002865  Title: Download Security Update for Microsoft Excel 2016 (64-bit edition), Content:, 1 link Security Update  Title: Build numbers, Content: 16.0.5552.1000 Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Excel 2016 (32-bit edition) - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Excel 2016 (32-bit edition), Content:, 1 link 5002865  Title: Download Security Update for Microsoft Excel 2016 (32-bit edition), Content:, 1 link Security Update  Title: Build numbers, Content: 16.0.5552.1000 Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Office LTSC for Mac 2024 - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Office LTSC for Mac 2024, Content:, 1 link Release Notes  Title: Download Security Update for Microsoft Office LTSC for Mac 2024, Content:, 1 link Security Update  Title: Build numbers, Content: 16.109.26051019 Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Office LTSC 2024 for 64-bit editions - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Office LTSC 2024 for 64-bit editions, Content:, 1 link Click to Run  Title: Download Security Update for Microsoft Office LTSC 2024 for 64-bit editions, Content:, 1 link Security Update Title: Build numbers, Content: https://aka.ms/OfficeSecurityReleases Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Office LTSC 2024 for 32-bit editions - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Office LTSC 2024 for 32-bit editions, Content:, 1 link Click to Run  Title: Download Security Update for Microsoft Office LTSC 2024 for 32-bit editions, Content:, 1 link Security Update Title: Build numbers, Content: https://aka.ms/OfficeSecurityReleases Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Office LTSC 2021 for 32-bit editions - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Office LTSC 2021 for 32-bit editions, Content:, 1 link Click to Run  Title: Download Security Update for Microsoft Office LTSC 2021 for 32-bit editions, Content:, 1 link Security Update Title: Build numbers, Content: https://aka.ms/OfficeSecurityReleases Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Office LTSC 2021 for 64-bit editions - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Office LTSC 2021 for 64-bit editions, Content:, 1 link Click to Run  Title: Download Security Update for Microsoft Office LTSC 2021 for 64-bit editions, Content:, 1 link Security Update Title: Build numbers, Content: https://aka.ms/OfficeSecurityReleases Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Office LTSC for Mac 2021 - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Office LTSC for Mac 2021, Content:, 1 link Release Notes  Title: Download Security Update for Microsoft Office LTSC for Mac 2021, Content:, 1 link Security Update  Title: Build numbers, Content: 16.109.26051019 Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft 365 Apps for Enterprise for 64-bit Systems - Information Disclosure Important Title: Knowledge Base Articles for Microsoft 365 Apps for Enterprise for 64-bit Systems, Content:, 1 link Click to Run  Title: Download Security Update for Microsoft 365 Apps for Enterprise for 64-bit Systems, Content:, 1 link Security Update Title: Build numbers, Content: https://aka.ms/OfficeSecurityReleases Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft 365 Apps for Enterprise for 32-bit Systems - Information Disclosure Important Title: Knowledge Base Articles for Microsoft 365 Apps for Enterprise for 32-bit Systems, Content:, 1 link Click to Run  Title: Download Security Update for Microsoft 365 Apps for Enterprise for 32-bit Systems, Content:, 1 link Security Update Title: Build numbers, Content: https://aka.ms/OfficeSecurityReleases Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Office 2019 for 64-bit editions - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Office 2019 for 64-bit editions, Content:, 1 link Click to Run  Title: Download Security Update for Microsoft Office 2019 for 64-bit editions, Content:, 1 link Security Update Title: Build numbers, Content: https://aka.ms/OfficeSecurityReleases Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Microsoft Office 2019 for 32-bit editions - Information Disclosure Important Title: Knowledge Base Articles for Microsoft Office 2019 for 32-bit editions, Content:, 1 link Click to Run  Title: Download Security Update for Microsoft Office 2019 for 32-bit editions, Content:, 1 link Security Update Title: Build numbers, Content: https://aka.ms/OfficeSecurityReleases Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required Title: Release date, Content: May 12, 2026 Office Online Server - Information Disclosure Important Title: Knowledge Base Articles for Office Online Server, Content:, 1 link 5002871  Title: Download Security Update for Office Online Server, Content:, 1 link Security Update  Title: Build numbers, Content: 16.0.10417.20128 Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required All results loaded Loaded all 13 rows Disclaimer The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. 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