CVE-2014-2730 in Office
Summary
by MITRE
The XML parser in Microsoft Office 2007 SP3, 2010 SP1 and SP2, and 2013, and Office for Mac 2011, does not properly detect recursion during entity expansion, which allows remote attackers to cause a denial of service (memory consumption and persistent application hang) via a crafted XML document containing a large number of nested entity references, as demonstrated by a crafted text/plain e-mail message to Outlook, a similar issue to CVE-2003-1564.
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Analysis
by VulDB Data Team • 05/09/2026
The vulnerability described in CVE-2014-2730 represents a classic recursive entity expansion flaw within Microsoft Office's XML processing capabilities. This issue affects multiple versions of Microsoft Office including 2007 SP3, 2010 SP1 and SP2, 2013, and Office for Mac 2011, demonstrating the widespread nature of this XML parser weakness that has persisted across different Office iterations. The vulnerability stems from insufficient validation mechanisms within the XML parser that fail to properly monitor and limit the depth of entity expansion during document parsing operations. This weakness creates a condition where maliciously crafted XML documents can trigger unlimited recursive entity expansion, leading to excessive memory consumption and application instability.
The technical exploitation of this vulnerability occurs when a malicious XML document containing deeply nested entity references is processed by Microsoft Office applications. When the XML parser encounters these recursive entity references, it continues expanding entities without proper depth limits or memory consumption monitoring, causing the application to consume excessive system resources. The attack vector typically involves sending a specially crafted text/plain email message to Outlook, which automatically processes the embedded XML content during rendering or parsing operations. This behavior aligns with CWE-400, which categorizes the vulnerability as an Uncontrolled Resource Consumption issue, specifically related to improper handling of recursive data structures.
The operational impact of this vulnerability manifests as persistent application hangs and significant memory consumption that can render Microsoft Office applications unusable. Attackers can maintain control over the affected system by keeping the application in a hung state, effectively creating a denial of service condition that prevents legitimate users from accessing their email or document processing capabilities. The vulnerability's similarity to CVE-2003-1564 indicates a recurring pattern in XML parser implementations where recursive entity expansion is not properly constrained, suggesting that this represents a fundamental architectural weakness rather than an isolated incident. This type of vulnerability falls under the ATT&CK technique T1499.004, which describes Resource Exhaustion, specifically focusing on denial of service through memory consumption.
The mitigation strategies for this vulnerability require both immediate patching and defensive configuration measures. Microsoft released security updates that addressed the recursive entity expansion issue by implementing proper depth limits and memory consumption monitoring within the XML parser. Organizations should prioritize applying these patches to all affected Office versions to eliminate the risk of exploitation. Additionally, implementing email filtering rules that block or quarantine suspicious XML content can provide an additional layer of defense. Security administrators should also consider disabling automatic XML processing in email clients where possible, and implementing monitoring for unusual memory consumption patterns in Office applications. The vulnerability highlights the importance of proper input validation and resource management in XML processing libraries, emphasizing the need for robust boundary checking mechanisms that prevent unlimited recursion in entity expansion operations.