CVE-2026-63515 in Office
Summary
by MITRE • 08/11/2026
Out-of-bounds read in Microsoft Office 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 memory safety issue within Microsoft Office applications that enables remote code execution through crafted malicious documents. The out-of-bounds read flaw occurs when the application fails to properly validate input data during document parsing operations, specifically affecting office file formats such as docx, xlsx, and pptx. When a user opens a specially crafted document containing malformed data structures, the application attempts to access memory locations beyond the allocated buffer boundaries. This memory access violation can be exploited by attackers to manipulate program execution flow and ultimately achieve arbitrary code execution on the target system.
The technical implementation of this vulnerability stems from insufficient bounds checking mechanisms within Microsoft Office's document parsing libraries. When processing structured office files, the software reads data elements without adequate validation of array indices or buffer limits, creating opportunities for attackers to craft inputs that trigger memory access violations. The flaw typically manifests during parsing operations where the application attempts to read beyond allocated memory regions, potentially leading to information disclosure or code execution depending on the specific implementation details and memory layout. This type of vulnerability aligns with common weakness enumeration CWE-129 and follows patterns identified in the attack pattern taxonomy under CWE-787.
The operational impact of this vulnerability extends far beyond simple exploitation scenarios as it provides attackers with persistent access to target systems through social engineering campaigns targeting end users. Attackers can distribute malicious office documents via email phishing campaigns, compromised websites, or malicious file sharing platforms, where unsuspecting users inadvertently open infected files. Once executed, the remote code execution capability allows threat actors to establish backdoors, escalate privileges, install additional malware, and maintain long-term access to compromised systems. The vulnerability's local execution requirement means that successful exploitation does not require network connectivity after initial compromise, making it particularly dangerous for enterprise environments where users may be browsing untrusted content or opening documents from external sources.
Organizations should implement multiple layers of defense to protect against this vulnerability including immediate application of Microsoft security patches and updates as released through regular security bulletins. Network segmentation and email filtering solutions should be enhanced to detect and block suspicious office document attachments, while endpoint protection systems should be configured to monitor for anomalous behavior patterns that may indicate exploitation attempts. User awareness training programs must emphasize the importance of verifying document sources before opening files, particularly those received via email or downloaded from unknown websites. Regular security assessments and vulnerability scanning should include checks for unpatched office applications, with particular attention to legacy systems that may not receive automatic updates. The mitigation strategy should also incorporate monitoring for suspicious process creation patterns and memory access violations that could indicate exploitation attempts, aligning with defensive practices outlined in the mitre attack framework's execution and privilege escalation tactics.