CVE-2009-0563 in Office Word Viewer
Summary
by MITRE
Stack-based buffer overflow in Microsoft Office Word 2002 SP3, 2003 SP3, and 2007 SP1 and SP2; Microsoft Office for Mac 2004 and 2008; Open XML File Format Converter for Mac; Microsoft Office Word Viewer 2003 SP3; Microsoft Office Word Viewer; and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2 allows remote attackers to execute arbitrary code via a Word document with a crafted tag containing an invalid length field, aka "Word Buffer Overflow Vulnerability."
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 04/22/2026
This vulnerability represents a critical stack-based buffer overflow affecting multiple versions of Microsoft Office products including Word 2002 SP3, 2003 SP3, 2007 SP1 and SP2, Office for Mac 2004 and 2008, Open XML File Format Converter for Mac, Word Viewer 2003 SP3, Word Viewer, and the Office Compatibility Pack. The flaw manifests when processing Word documents containing crafted tags with invalid length fields, creating a condition where attacker-controlled data can overwrite adjacent memory locations on the stack. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue where insufficient bounds checking allows data to overflow into adjacent memory regions. The vulnerability operates through the parsing of structured document formats, specifically targeting the Office Word document parser's handling of malformed tag length parameters.
The technical execution of this vulnerability occurs when Microsoft Office applications process Word documents containing specially crafted malicious tags with incorrect length fields. During document parsing, the application's buffer management fails to validate the length field of these tags, allowing an attacker to provide a value that exceeds the allocated buffer size. When the application attempts to copy data into the buffer using this invalid length, it overflows the stack space allocated for the operation, potentially overwriting return addresses, function pointers, and other critical stack data. This overflow can be exploited to redirect program execution flow to malicious code injected by the attacker, enabling arbitrary code execution with the privileges of the victim user. The attack vector is particularly dangerous because it requires no user interaction beyond opening the malicious document, making it a prime candidate for phishing attacks and remote code execution scenarios.
The operational impact of this vulnerability is severe and multifaceted across enterprise environments where Microsoft Office is widely deployed. Successful exploitation can result in complete system compromise, allowing attackers to execute arbitrary commands on vulnerable systems, escalate privileges, and potentially establish persistent backdoors. The vulnerability affects both Windows and Mac operating systems, expanding the attack surface significantly. Organizations using older versions of Office products face the greatest risk as these legacy applications often lack modern exploit mitigation features. The vulnerability's remote exploitation capability makes it particularly attractive to threat actors targeting corporate networks, as it can be delivered through email attachments, web downloads, or malicious document sharing. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, representing a classic privilege escalation and execution vector.
Mitigation strategies for this vulnerability should focus on immediate remediation through Microsoft security updates and patches, which address the underlying buffer overflow in the document parsing logic. Organizations should implement comprehensive patch management policies ensuring all Office installations receive timely updates from Microsoft. Network-based mitigations including email filtering and document inspection systems can help prevent delivery of malicious documents to end users. Additionally, implementing application whitelisting policies and disabling automatic document opening in email clients can reduce exploitation success rates. Security awareness training for users to recognize suspicious email attachments and document files remains crucial. System hardening measures such as enabling Data Execution Prevention (DEP), Address Space Layout Randomization (ASLR), and using sandboxing techniques can provide additional defense layers against exploitation attempts. Regular vulnerability assessments and penetration testing should be conducted to identify unpatched systems and ensure proper implementation of security controls. Organizations should also consider implementing zero-trust network architectures that limit lateral movement even if initial exploitation occurs, reducing the potential impact of successful attacks.