CVE-2020-1338 in Office
Summary
by MITRE
<p>A remote code execution vulnerability exists in Microsoft Word software when it fails to properly handle objects in memory. An attacker who successfully exploited the vulnerability could use a specially crafted file to perform actions in the security context of the current user. For example, the file could then take actions on behalf of the logged-on user with the same permissions as the current user.</p> <p>To exploit the vulnerability, a user must open a specially crafted file with an affected version of Microsoft Word software. In an email attack scenario, an attacker could exploit the vulnerability by sending the specially crafted file to the user and convincing the user to open the file. In a web-based attack scenario, an attacker could host a website (or leverage a compromised website that accepts or hosts user-provided content) that contains a specially crafted file that is designed to exploit the vulnerability. However, an attacker would have no way to force the user to visit the website. Instead, an attacker would have to convince the user to click a link, typically by way of an enticement in an email or Instant Messenger message, and then convince the user to open the specially crafted file.</p> <p>The security update addresses the vulnerability by correcting how Microsoft Word handles files in memory.</p>
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Analysis
by VulDB Data Team • 02/24/2026
The vulnerability identified as CVE-2020-1338 represents a critical remote code execution flaw in Microsoft Word software that stems from improper handling of memory objects during file processing operations. This weakness falls under the broader category of memory corruption vulnerabilities and aligns with CWE-125, which describes out-of-bounds read conditions that can lead to arbitrary code execution. The vulnerability exists in the way Microsoft Word parses and manages objects within memory when processing specially crafted files, creating a pathway for attackers to execute malicious code with the privileges of the currently logged-on user. The flaw demonstrates characteristics consistent with the attack techniques documented in the MITRE ATT&CK framework under T1203 - Exploitation for Client Execution, where adversaries leverage software vulnerabilities to execute malicious code on target systems.
The exploitation mechanism for CVE-2020-1338 requires user interaction through the opening of a maliciously crafted file, making it particularly dangerous in social engineering contexts. Attackers can deliver the malicious payload through various vectors including email attachments, web-based delivery, or compromised websites that host the specially crafted files. The attack chain typically begins with an attacker crafting a file that triggers the memory handling flaw when opened by Microsoft Word, followed by the execution of arbitrary code within the user's security context. This approach aligns with the ATT&CK technique T1068 - Exploitation for Privilege Escalation, where initial access through file execution leads to potential privilege escalation within the compromised system. The vulnerability's impact is significant as it allows for complete system compromise when the user opens the malicious document, since the code executes with the same permissions as the current user.
The operational impact of CVE-2020-1338 extends beyond simple code execution to encompass potential data theft, system reconnaissance, and further lateral movement within network environments. When successfully exploited, the vulnerability enables attackers to perform actions such as creating new user accounts, installing additional malware, accessing sensitive files, or establishing persistent access through backdoor mechanisms. The memory corruption nature of the vulnerability means that attackers can potentially bypass many traditional security controls that rely on proper input validation and memory management. Organizations running affected versions of Microsoft Word are particularly vulnerable since the attack requires no special privileges or network access beyond the ability to deliver the malicious file to a target user, making it a preferred vector for targeted attacks against enterprise environments. The vulnerability's exploitability is further enhanced by the widespread use of Microsoft Word across corporate networks, creating a large attack surface for threat actors.
Microsoft's security update for CVE-2020-1338 addresses the root cause by modifying the memory handling procedures within Microsoft Word to properly validate and manage objects during file processing. The fix involves implementing additional safeguards to prevent the memory corruption that enables the remote code execution, including enhanced input validation and improved memory allocation routines. Organizations should prioritize immediate deployment of the security update across all affected systems to mitigate the risk of exploitation. Additional mitigation strategies include implementing email filtering solutions to detect and block suspicious attachments, disabling automatic opening of Office documents from untrusted sources, and conducting user awareness training to recognize social engineering attempts. The vulnerability also underscores the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies that include network monitoring, endpoint detection and response capabilities, and regular security assessments to identify and remediate similar memory corruption vulnerabilities before they can be exploited by adversaries.