CVE-2026-70214 in Office
Summary
by MITRE • 10/14/2026
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 • 10/14/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office Excel application, specifically categorized as an out-of-bounds read error. This type of memory corruption issue arises when the software attempts to access data stored at a memory location that is outside the boundaries of the intended buffer or array structure. In the context of spreadsheet processing engines like those found in Excel, such errors typically occur during the parsing and rendering of complex document structures, formulas, or embedded objects where input validation mechanisms fail to properly verify index values against allocated memory limits. When an attacker crafts a malicious file containing specifically designed malformed data, they can trigger this condition by causing the application to read from invalid memory addresses that were not intended for access.
From a technical perspective, out-of-bounds reads are distinct from buffer overflows because they generally do not allow for arbitrary code execution or direct control of program flow through stack smashing. Instead, their primary impact lies in information disclosure. By exploiting this flaw, an unauthorized attacker who has local access to the system can cause Excel to leak sensitive data residing adjacent to the targeted memory region into a location where it can be observed or extracted. This could include partial contents of other open documents, cryptographic keys stored in memory, session tokens, or internal application states that were not meant to be exposed to external processes. The severity of this disclosure depends heavily on what specific data resides in the adjacent memory space at the time of exploitation, but it fundamentally compromises the confidentiality guarantees expected by users handling sensitive spreadsheets containing financial records, personal identifiable information, or proprietary business logic.
The operational impact of this vulnerability is significant for organizations relying on Excel for critical data processing. Since the attack vector requires local access, it poses a heightened risk in environments where multiple users share workstations or when social engineering tactics are employed to trick a privileged user into opening a malicious file. Once triggered, the exploitation does not necessarily crash the application immediately, which may allow the attacker to perform repeated reads and gather substantial amounts of data over time without raising immediate suspicion through system instability. This stealthy nature makes it particularly dangerous in scenarios involving insider threats or compromised local accounts where an adversary seeks to exfiltrate sensitive information from memory before moving laterally across a network.
To mitigate this risk, organizations must ensure that Microsoft Office Excel is updated with the latest security patches released by Microsoft, as these updates typically include rigorous input validation checks and bounds checking routines designed to prevent access to unauthorized memory regions. Administrators should enforce strict software update policies to guarantee that all endpoints running vulnerable versions of Office are patched promptly. Additionally, implementing application control solutions such as AppLocker or Windows Defender Application Control can restrict the execution of untrusted scripts and macros often used in conjunction with exploit payloads. Users should be trained to exercise caution when opening files from unknown sources, particularly those containing complex formulas or embedded objects that might trigger parsing anomalies. Regular security awareness training combined with technical controls significantly reduces the attack surface available for exploiting memory corruption vulnerabilities like this out-of-bounds read flaw.