# CVE-2026-55122: Microsoft Excel out-of-bounds read information disclosure Source: https://junglewise.ai/threats/cve-2026-55122-microsoft-excel-out-of-bounds-read-information-disclosure Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats Published: 2026-07-14. Updated: 2026-07-14 License: CC BY 4.0 with a link back CVE-2026-55122 · Severity: high · CVSS 7.1 · Published 2026-07-14 A security vulnerability exists in Microsoft Excel, the widely used spreadsheet application. If a user is tricked into opening a specially crafted file, an attacker could gain access to sensitive information stored in the computer's memory or cause the application to crash. This could lead to the exposure of confidential data or disrupt business operations by making the software unavailable. Technologies: [Microsoft 365 Apps for Enterprise](https://junglewise.ai/threats/technologies/365-apps-for-enterprise), [Microsoft Excel 2016](https://junglewise.ai/threats/technologies/excel-2016), [Microsoft Office 2019](https://junglewise.ai/threats/technologies/office-2019), [Microsoft Office 365 for Mac](https://junglewise.ai/threats/technologies/office-365-for-mac), [Microsoft Office LTSC 2021](https://junglewise.ai/threats/technologies/office-ltsc-2021), [Microsoft Office LTSC 2024](https://junglewise.ai/threats/technologies/office-ltsc-2024), [Microsoft Office Online Server](https://junglewise.ai/threats/technologies/office-online-server). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft). ## Quick answers **Is CVE-2026-55122 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55122 being exploited in the wild. **How severe is CVE-2026-55122?** High severity, with a CVSS score of 7.1, published 14 July 2026. **Which products and versions are affected?** Microsoft 365 Apps for Enterprise versions prior to July 2026 updates; Microsoft Excel 2016 versions prior to 16.0.5561.1001; Microsoft Office 2019 versions prior to July 2026 updates; Microsoft Office 365 for Mac versions prior to 16.111.26071215; and 3 more. **Is there a fix for CVE-2026-55122?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it. **How is CVE-2026-55122 attacked?** It is attacked with local access, in a network appliance. **Am I affected by CVE-2026-55122?** Check whether you run Microsoft 365 Apps for Enterprise, Microsoft Excel 2016, Microsoft Office 2019 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you. ## Technical details An out-of-bounds read vulnerability (CWE-125) exists in Microsoft Excel due to improper validation of data when parsing specially crafted files. An attacker can exploit this by convincing a user to open a malicious Excel file, leading to the disclosure of sensitive information from the process memory or an application crash (denial of service). The attack vector is local, but requires user interaction (UI:R) to trigger the flaw. Affected products include various versions of Microsoft Office, Excel 2016, and Office Online Server. Microsoft has released security updates to address this issue. ## Affected products - Microsoft Microsoft 365 Apps for Enterprise versions prior to July 2026 updates - Microsoft Microsoft Excel 2016 versions prior to 16.0.5561.1001 - Microsoft Microsoft Office 2019 versions prior to July 2026 updates - Microsoft Microsoft Office 365 for Mac versions prior to 16.111.26071215 - Microsoft Microsoft Office LTSC 2021 / 2024 versions prior to July 2026 updates - Microsoft Office Online Server versions prior to 16.0.10417.20175 ## Timeline - 2026-07-14: disclosed: Initial publication of the CVE record. - 2026-07-14: advisory: Microsoft released the security update guide for this vulnerability. ## References - [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55122](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55122) ## Related threats - [Microsoft Office Excel out-of-bounds read in parsing](https://junglewise.ai/threats/cve-2026-105718-out-of-bounds-read-in-microsoft-office-excel-allows-an) - [Microsoft Office Excel use-after-free remote code execution](https://junglewise.ai/threats/cve-2026-100212-use-after-free-in-microsoft-office-excel-allows-an-unauthorized) - [Microsoft Office Excel heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-100210-heap-based-buffer-overflow-in-microsoft-office-excel-allows-an) - [Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information locally.](https://junglewise.ai/threats/cve-2026-70310-out-of-bounds-read-in-microsoft-office-word-allows-an) - [Microsoft Office out-of-bounds read information disclosure](https://junglewise.ai/threats/cve-2026-56195-microsoft-office-out-of-bounds-read-information-disclosure)