CVE-2020-0696 in Office
Summary
by MITRE
A security feature bypass vulnerability exists in Microsoft Outlook software when it improperly handles the parsing of URI formats, aka 'Microsoft Outlook Security Feature Bypass Vulnerability'.
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Analysis
by VulDB Data Team • 05/11/2025
The CVE-2020-0696 vulnerability represents a critical security feature bypass in Microsoft Outlook software that stems from improper handling of URI format parsing within the application's security mechanisms. This flaw specifically affects Microsoft Outlook versions prior to the security updates released in June 2020, creating a pathway for malicious actors to circumvent intended security controls. The vulnerability resides in how Outlook processes Uniform Resource Identifiers, particularly when these URIs contain specific formatting patterns that the application fails to properly validate or sanitize. This improper parsing behavior allows attackers to manipulate the application's security checks, potentially enabling unauthorized access to email content or bypassing protective measures designed to prevent malicious code execution.
The technical nature of this vulnerability aligns with CWE-20, which describes improper input validation, and demonstrates how URI parsing flaws can lead to security feature bypasses. When Outlook encounters specially crafted URIs in email messages, the application's parsing logic fails to correctly interpret the format, resulting in the security controls being effectively neutralized. This issue is particularly concerning because it operates at the application layer where email clients process potentially malicious content from untrusted sources. The vulnerability can be exploited through email messages containing maliciously formatted URIs that appear legitimate to users while simultaneously bypassing Outlook's built-in security mechanisms designed to detect and block potentially harmful content. The flaw essentially creates a condition where the application's security features become ineffective against crafted input that exploits parsing inconsistencies.
From an operational impact perspective, this vulnerability exposes organizations to significant risks including unauthorized access to sensitive email communications, potential data exfiltration, and increased attack surface for more sophisticated exploits. Security researchers have noted that the vulnerability can be leveraged to bypass Outlook's security features that typically prevent automatic execution of scripts or the loading of external resources from untrusted domains. Attackers can craft email messages with malicious URIs that, when processed by the vulnerable Outlook client, allow them to execute code or access resources that would normally be restricted. The impact extends beyond simple information disclosure as it can enable further compromise through phishing attacks, credential theft, or the deployment of additional malware. Organizations with extensive Outlook deployments face substantial risk exposure, particularly in environments where email remains a primary vector for cyber attacks.
Mitigation strategies for CVE-2020-0696 primarily focus on applying the relevant Microsoft security updates released in June 2020, which address the URI parsing inconsistencies that enable the bypass. System administrators should prioritize immediate deployment of the security patches, as the vulnerability can be exploited remotely without user interaction, making it particularly dangerous in enterprise environments. Additional protective measures include implementing email filtering solutions that can detect and block suspicious URI patterns, configuring Outlook to disable automatic loading of external content, and establishing security awareness training for users to recognize potentially malicious email content. Organizations should also consider implementing network-level controls that monitor for suspicious URI patterns and establish strict policies for handling email attachments and links. The vulnerability demonstrates the importance of proper input validation in email client applications and highlights the need for continuous security assessments of application parsing logic. Security teams should monitor for related exploitation attempts and maintain updated threat intelligence regarding similar URI-based vulnerabilities in other Microsoft products, as the underlying parsing issues may affect other components within the Microsoft Office suite.