CVE-2026-55046 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 • 07/14/2026
This vulnerability represents a critical out-of-bounds read flaw within Microsoft Office Excel that enables local attackers to extract sensitive information from memory locations beyond the intended buffer boundaries. The technical implementation involves improper input validation and boundary checking mechanisms within Excel's spreadsheet processing engine, specifically when handling malformed or specially crafted spreadsheet files. Such vulnerabilities typically arise from insufficient bounds checking during array or buffer operations, allowing arbitrary memory access patterns that can reveal confidential data including encryption keys, user credentials, or system information.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks such as privilege escalation or remote code execution when combined with other exploitation techniques. Attackers can leverage this flaw by crafting malicious spreadsheet files that trigger the out-of-bounds read condition during normal Excel operations. The vulnerability aligns with CWE-129, which specifically addresses improper validation of length parameters, and may also map to CWE-787 for out-of-bounds write conditions that could result from similar memory handling issues. From an adversary perspective, this flaw fits within the ATT&CK framework under T1059 for execution through scripting and potentially T1068 for local privilege escalation when combined with additional attack vectors.
The security implications are particularly severe in enterprise environments where Excel is commonly used for data processing and document sharing, as attackers can exploit this vulnerability through social engineering campaigns distributing malicious spreadsheets via email or compromised collaboration platforms. The flaw demonstrates a fundamental weakness in Microsoft's input sanitization processes within the Office suite, highlighting the importance of proper memory management practices and robust boundary checking implementations. Organizations should implement immediate mitigations including applying security patches from Microsoft, deploying application control measures to restrict Excel execution in sensitive environments, and conducting thorough vulnerability assessments of existing spreadsheet files. Additionally, network segmentation and monitoring solutions should be enhanced to detect suspicious file access patterns that might indicate exploitation attempts targeting this specific vulnerability.
This type of memory corruption vulnerability represents a persistent challenge in software security, particularly within complex applications like Microsoft Office that process vast amounts of user data through multiple parsing layers. The out-of-bounds read condition can potentially expose sensitive information stored in adjacent memory locations, making it particularly dangerous for attackers seeking to extract system configuration details or user session data. Security professionals must recognize this vulnerability pattern as part of broader defensive strategies focusing on memory safety and input validation controls that align with industry best practices established by organizations such as the Open Web Application Security Project and the National Institute of Standards and Technology.