CVE-2026-55128 in Office
Summary
by MITRE • 07/14/2026
Use after free in Microsoft Office Word allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/15/2026
This vulnerability represents a critical use-after-free condition in Microsoft Office Word that enables arbitrary code execution through local privilege escalation. The flaw occurs when the application improperly handles memory management during document processing operations, specifically when dealing with certain object references after they have been freed from memory. Attackers can exploit this by crafting malicious Word documents that trigger the vulnerable code path, causing the application to reference freed memory locations. This memory corruption allows attackers to execute arbitrary code within the context of the currently logged-on user, potentially leading to full system compromise. The vulnerability stems from inadequate input validation and memory management practices during document parsing operations, where the Word application fails to properly track object lifecycles and validate memory references before dereferencing them.
The technical nature of this exploit aligns with common software security weaknesses classified under CWE-416, which addresses use-after-free vulnerabilities in memory management. This weakness specifically targets improper handling of memory objects after their release, creating opportunities for attackers to manipulate freed memory regions. From an operational perspective, the attack requires minimal user interaction beyond opening a malicious document, making it particularly dangerous in targeted phishing campaigns or social engineering attacks. The vulnerability affects multiple versions of Microsoft Office Word and demonstrates poor adherence to secure coding practices such as those recommended by the OWASP Secure Coding Practices and the CERT Secure Coding Standards. Attackers can leverage this vulnerability to bypass traditional security controls like user access controls and execute malicious payloads directly within the application's memory space.
The operational impact extends beyond simple code execution, as successful exploitation can lead to complete system compromise through privilege escalation attacks. Once executed, malicious code can establish persistence mechanisms, exfiltrate sensitive data, or create backdoor access points for further network infiltration. The vulnerability also poses significant risk in enterprise environments where users frequently open documents from untrusted sources, making it a prime target for advanced persistent threat actors and nation-state attackers. Security professionals should note that this type of vulnerability often requires immediate patch management responses due to its high severity classification and the availability of public exploit code. Mitigation strategies include implementing strict document validation policies, deploying application whitelisting solutions, and ensuring timely security updates are applied across all affected systems. Organizations should also consider network segmentation and user education programs to reduce the attack surface and prevent accidental exploitation through social engineering tactics that commonly deliver these malicious documents.