CVE-2026-55055 in Office
Summary
by MITRE • 07/14/2026
Stack-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/15/2026
A stack-based buffer overflow vulnerability in Microsoft Office Word represents a critical security flaw that enables remote code execution when a maliciously crafted document is opened by an unsuspecting user. This vulnerability stems from improper input validation within the word processing application's handling of specific file format elements, particularly those related to document parsing and memory allocation. The flaw occurs when the application attempts to write data beyond the bounds of a predetermined stack buffer, creating opportunities for attackers to overwrite critical memory locations including return addresses and function pointers.
The technical implementation of this vulnerability involves the exploitation of memory corruption patterns that allow adversaries to manipulate program execution flow by overwriting the stack frame of executing functions. Attackers can craft malicious Word documents containing specially formatted data structures that trigger the buffer overflow during normal document processing operations, typically when parsing embedded objects, tables, or formatting elements. The attack vector requires user interaction through opening the malicious file, making it a typical social engineering target that aligns with ATT&CK technique T1204.002 for legitimate user execution.
This vulnerability presents significant operational impact across enterprise environments where Microsoft Office remains the standard productivity suite, as it enables attackers to establish persistent footholds on systems without requiring elevated privileges initially. The local code execution capability allows threat actors to install backdoors, exfiltrate data, or escalate privileges through subsequent exploitation attempts. Organizations utilizing default security configurations face heightened risk since the vulnerability can be exploited through simple document sharing mechanisms including email attachments and web downloads.
Mitigation strategies should emphasize comprehensive patch management programs with immediate deployment of Microsoft security updates addressing the specific buffer overflow conditions. Network segmentation and email filtering solutions can reduce exposure by blocking suspicious document types and implementing sandboxing for document analysis before user access. Security awareness training becomes crucial in preventing successful exploitation through social engineering approaches, while endpoint detection and response systems should monitor for anomalous memory allocation patterns and process execution behaviors associated with exploitation attempts. The vulnerability aligns with CWE-121 stack-based buffer overflow classification and represents a common target for threat actors seeking to establish initial access within enterprise networks according to ATT&CK framework's initial access tactics.