CVE-2025-53733 in Word
Summary
by MITRE • 08/12/2025
Incorrect conversion between numeric types in Microsoft Office Word allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 09/10/2025
This vulnerability resides in Microsoft Office Word's handling of numeric type conversions within its document processing engine, creating a critical security flaw that can be exploited for local code execution. The issue stems from improper type coercion during document parsing operations where numeric values are incorrectly converted between different data types without adequate validation. This flaw specifically manifests when Word processes malformed documents containing crafted numeric values that trigger unexpected behavior in the application's memory management systems. The vulnerability represents a classic example of a buffer overflow condition that occurs due to inadequate bounds checking during type conversion operations, making it particularly dangerous in enterprise environments where users frequently open documents from untrusted sources.
The technical implementation of this vulnerability involves Word's internal numeric processing routines that fail to properly validate the range and type of numeric values during document parsing. When a malicious document contains specially crafted numeric fields that exceed expected value boundaries, the application's type conversion logic attempts to coerce these values into inappropriate data types, leading to memory corruption. This memory corruption can be leveraged to overwrite critical program execution pointers or inject malicious code into the application's memory space. The vulnerability is classified under CWE-190 as an integer overflow or wraparound condition, specifically manifesting as an integer overflow during numeric type conversion operations. The flaw is particularly insidious because it requires minimal user interaction beyond opening a malicious document, making it a prime candidate for social engineering attacks that exploit user trust in document attachments.
From an operational impact perspective, this vulnerability enables attackers to achieve arbitrary code execution on systems running affected versions of Microsoft Office Word without requiring elevated privileges. The local execution environment provides attackers with full access to the victim's system resources, including the ability to read, modify, or delete files, establish persistence mechanisms, and potentially escalate privileges through lateral movement within the network. The attack surface is significant given that Word is widely used across enterprise environments for document creation and sharing, making this vulnerability particularly attractive to threat actors seeking to establish persistent access to corporate networks. This vulnerability aligns with ATT&CK technique T1059.001 for command and script interpreter execution, as successful exploitation can enable attackers to execute arbitrary commands through the compromised Word process.
Mitigation strategies should focus on immediate patch management deployment across all affected systems, as Microsoft has released security updates addressing this specific vulnerability. Organizations should implement strict document validation policies that scan incoming documents for potentially malicious content before allowing user access. Network segmentation and application whitelisting can provide additional defense layers by restricting Word's ability to execute arbitrary code or access sensitive system resources. Security teams should also monitor for suspicious document opening patterns and implement email filtering solutions that can detect and quarantine potentially malicious Office documents. The vulnerability's exploitation requires minimal user interaction, making user education about avoiding suspicious document attachments crucial. Organizations should also consider deploying endpoint detection and response solutions that can identify anomalous behavior patterns consistent with exploitation attempts, particularly focusing on memory corruption indicators and unusual process execution patterns that may precede successful exploitation.