CVE-2026-63519 in Office
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/11/2026
A heap-based buffer overflow vulnerability exists within Microsoft Office applications that enables unauthorized remote code execution when a maliciously crafted file is opened by an unsuspecting user. This critical flaw resides in the memory management handling of specific file formats processed by office applications, particularly affecting word processing documents, spreadsheets, and presentation files. The vulnerability stems from inadequate bounds checking during heap allocation operations where insufficient validation allows attackers to overwrite adjacent memory locations with malicious code payloads. When a user opens an infected document, the application attempts to parse the malformed data structure which triggers the buffer overflow condition in the heap memory region. This memory corruption can be exploited to redirect program execution flow to attacker-controlled code, bypassing standard security mechanisms including data execution prevention and address space layout randomization. The vulnerability impacts multiple Microsoft Office versions across different operating systems including windows 7 through windows 11 and office 2016 through office 2021. According to cwe-129, this represents a weakness in input validation where insufficient length checks allow buffer overflows. The attack vector typically involves social engineering tactics where users are tricked into opening malicious attachments delivered via email phishing campaigns or compromised websites. From an attacker perspective, this vulnerability maps directly to the execution phase of the kill chain under the mitre att&ck framework with techniques such as command and script interpreter for code execution. The operational impact includes potential full system compromise, data exfiltration, persistence mechanisms establishment, and lateral movement within network environments. Organizations face significant risk exposure since office applications remain widely used across enterprise environments and user endpoints, making this vulnerability particularly attractive to threat actors seeking persistent access. Microsoft has addressed this issue through security updates and patches that implement proper bounds checking and memory validation procedures. Recommended mitigations include immediate deployment of microsoft security updates, implementation of email filtering solutions to block suspicious attachments, user education regarding phishing awareness, application whitelisting policies, and network segmentation to limit lateral movement capabilities. Additionally, enabling exploit protection features such as control flow guard and runtime application checks can provide additional defense layers against exploitation attempts. The vulnerability highlights the ongoing challenge of memory safety issues in complex software applications and underscores the importance of robust input validation practices throughout the software development lifecycle.