CVE-2021-42293 in Office
Summary
by MITRE • 12/15/2021
Microsoft Jet Red Database Engine and Access Connectivity Engine Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 05/19/2026
The CVE-2021-42293 vulnerability represents a critical elevation of privilege flaw affecting Microsoft Jet Red Database Engine and Access Connectivity Engine components. This vulnerability resides in the way these database engines handle certain file operations and memory management processes, creating opportunities for malicious actors to escalate their privileges within affected systems. The flaw specifically impacts versions of Microsoft Office and Office Online that utilize these database engines for data storage and retrieval operations. Security researchers identified this issue through comprehensive analysis of the engine's internal processing mechanisms, particularly focusing on how it manages temporary file creation and resource allocation during database operations. The vulnerability affects systems running Windows operating systems where these database components are installed, including both desktop and server environments that may utilize Microsoft Access or related database functionalities.
The technical implementation of this privilege escalation vulnerability stems from improper validation of file paths and insufficient access controls during database engine operations. When the Jet Red Database Engine processes certain database files or executes specific queries, it creates temporary files in predictable locations without adequate security checks. Attackers can exploit this by manipulating database content or creating malicious database files that trigger the vulnerable code path. The flaw allows an attacker with limited user privileges to execute arbitrary code with elevated system privileges, effectively bypassing standard security boundaries. This occurs because the database engine performs operations that do not properly validate user input or enforce proper access controls, particularly when handling external database connections or file references. The vulnerability is classified under CWE-264, which addresses permissions, privileges, and access controls, specifically focusing on inadequate access control mechanisms in database processing components. This weakness enables attackers to manipulate the execution flow of database operations and gain unauthorized system-level access.
The operational impact of CVE-2021-42293 extends significantly across enterprise environments where Microsoft Office and Access Connectivity Engine components are prevalent. Organizations utilizing legacy database systems or older versions of Microsoft Office products face heightened risk of compromise, as these systems often lack the security mitigations present in updated releases. Attackers can leverage this vulnerability to establish persistent backdoors, escalate privileges to SYSTEM level access, and potentially move laterally within network environments. The vulnerability is particularly concerning for environments with default installations of Microsoft Office, as these typically include the affected database engines by default. Security teams must consider that exploitation of this vulnerability can occur through various attack vectors including phishing emails containing malicious database attachments, compromised web applications that process user-uploaded database files, or through direct exploitation of vulnerable Office installations. The attack surface is further expanded when considering that these database engines are often used in automated processes, web applications, and enterprise solutions that may not receive regular security updates, creating persistent exposure windows.
Mitigation strategies for CVE-2021-42293 should prioritize immediate patch deployment through Microsoft's security updates, which address the core privilege escalation mechanisms within the affected database engines. Organizations must implement comprehensive vulnerability management processes that include regular security assessments of Office installations and database engine usage patterns. Network segmentation and privilege separation should be enforced to limit potential exploitation impact, particularly for systems where database engines are not essential for core operations. Security monitoring should focus on detecting anomalous database file creation patterns, unexpected privilege escalation events, and unusual access to database engine processes. Additionally, organizations should consider implementing application whitelisting policies that restrict execution of database engine components outside of approved contexts. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the use of software vulnerabilities for privilege elevation. Organizations should also conduct regular security awareness training to prevent social engineering attacks that might deliver malicious database files designed to exploit this vulnerability. System hardening measures including disabling unnecessary database engine features, implementing strict file access controls, and regular security audits of database usage patterns provide additional defensive layers against exploitation attempts.