CVE-2026-55898 in Office
Summary
by MITRE • 07/14/2026
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
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Analysis
by VulDB Data Team • 07/15/2026
This vulnerability represents a critical out-of-bounds read flaw within Microsoft Office Excel that enables local attackers to extract sensitive information from the application's memory space. The issue manifests when Excel processes specially crafted spreadsheet files, causing the software to access memory locations beyond the intended boundaries of allocated data structures. This type of vulnerability falls under the common weakness enumeration CWE-125, which specifically addresses out-of-bounds read conditions that can lead to information disclosure and potential privilege escalation scenarios. The flaw exists in the parsing logic of Excel's file handling mechanisms, where insufficient bounds checking allows maliciously constructed data to trigger unauthorized memory access patterns.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with a foothold for more sophisticated attacks within the target system. When an attacker successfully exploits this weakness, they can potentially extract sensitive data such as memory addresses, encryption keys, or other confidential information that resides in adjacent memory locations. This type of attack aligns with techniques described in the attack pattern taxonomy under ATT&CK framework category TA0001, specifically targeting privilege escalation and credential access through memory corruption vulnerabilities. The local nature of this exploitation means that an attacker must already have some level of access to the system to craft and execute malicious spreadsheets, though the subsequent information disclosure can be leveraged for further compromise.
Security professionals should prioritize immediate remediation through Microsoft's security updates and patches, as this vulnerability represents a significant risk to enterprise environments where Excel is widely used for data processing. Organizations should implement additional defensive measures including restricted file execution policies, sandboxing of spreadsheet processing applications, and monitoring for unusual memory access patterns that might indicate exploitation attempts. The vulnerability underscores the importance of robust input validation and bounds checking in office productivity software, particularly given the widespread use of Microsoft Office applications across corporate networks where such flaws can serve as initial attack vectors for broader security breaches.