CVE-2026-64905 in Office
Summary
by MITRE • 08/11/2026
Buffer over-read in Microsoft Office Word allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical buffer over-read condition that exists within Microsoft Office Word applications, specifically affecting versions prior to the security patches released in 2023. The flaw manifests when the application processes specially crafted malicious documents, particularly those containing malformed or oversized data structures within word processing formats such as .docx or .doc files. This memory management error occurs during the parsing of document elements where insufficient bounds checking allows an attacker to read beyond allocated memory boundaries, potentially leading to arbitrary code execution on the target system. The vulnerability is classified under CWE-125 as an "Out-of-bounds Read" which falls within the broader category of memory safety issues that have long plagued software applications. The attack vector requires the victim to open a malicious document, making this a classic example of a user-initiated exploitation scenario that aligns with ATT&CK technique T1204.002 for "User Execution" and T1059.001 for "Command and Scripting Interpreter". When successfully exploited, the buffer over-read allows an attacker to execute code with the privileges of the targeted user, potentially leading to full system compromise through privilege escalation or lateral movement within a network environment.
The operational impact of this vulnerability extends beyond simple local code execution as it provides attackers with a powerful foothold for more sophisticated attacks. Once an attacker successfully exploits this vulnerability, they can establish persistent access through various techniques including the installation of backdoors, credential theft mechanisms, or additional malware payloads. The nature of this flaw makes it particularly dangerous in enterprise environments where users frequently open documents from untrusted sources, making the attack surface significantly larger than typical buffer overflow vulnerabilities. Security analysts have noted that attackers often leverage such vulnerabilities to create initial access points before moving laterally through networks, using the compromised system as a launching pad for further reconnaissance and data exfiltration activities. The vulnerability's prevalence across multiple Office versions means that organizations with legacy systems remain particularly at risk, as older versions may not receive security updates or patches.
Mitigation strategies for this vulnerability should encompass both immediate defensive measures and long-term architectural improvements. Organizations must prioritize urgent patch management procedures to ensure all Microsoft Office installations receive the latest security updates from Microsoft's monthly release cycle. Additionally, implementing application whitelisting solutions such as Windows Defender Application Control can prevent unauthorized executables from running even if exploitation occurs. Network-level defenses including email filtering systems should be enhanced to detect and quarantine suspicious document attachments that may contain malicious payloads. Security teams should also consider deploying endpoint detection and response (EDR) solutions that can monitor for anomalous behavior patterns consistent with buffer over-read exploitation attempts. According to NIST guidelines for secure software development, organizations should implement comprehensive input validation procedures and regular security code reviews to address similar vulnerabilities in custom applications. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches as highlighted in Microsoft's own security advisory practices, where timely patch deployment remains one of the most effective defense mechanisms against such memory corruption flaws that can lead to complete system compromise.