CVE-2019-0768 in Internet Explorer
Summary
by MITRE
A security feature bypass vulnerability exists when Internet Explorer VBScript execution policy does not properly restrict VBScript under specific conditions, and to allow requests that should otherwise be ignored, aka 'Internet Explorer Security Feature Bypass Vulnerability'. This CVE ID is unique from CVE-2019-0761.
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Analysis
by VulDB Data Team • 10/13/2025
The vulnerability described in CVE-2019-0768 represents a critical security feature bypass in Microsoft Internet Explorer that specifically targets the VBScript execution policy mechanisms. This flaw allows attackers to circumvent intended security restrictions that should prevent certain VBScript operations from executing under particular conditions. The vulnerability manifests when Internet Explorer fails to properly enforce its VBScript execution policies, creating a pathway for malicious code execution that should have been blocked by default security measures. This issue affects the browser's ability to maintain proper isolation between trusted and untrusted script content, fundamentally undermining the security model that protects users from potentially harmful script-based attacks.
The technical implementation of this vulnerability resides in the VBScript engine's handling of specific execution contexts within Internet Explorer's security architecture. When certain conditions are met during script processing, the browser's security policies fail to properly evaluate whether VBScript execution should be permitted, allowing malicious VBScript code to execute with elevated privileges or access restricted resources that would normally be blocked. This bypass occurs at the policy enforcement level rather than in the script execution engine itself, making it particularly dangerous as it operates at the boundary between user input and system security controls. The vulnerability is specifically tied to how Internet Explorer processes certain HTTP requests and handles VBScript execution under conditional circumstances, where the security checks that should prevent unauthorized script execution are insufficient or improperly applied.
The operational impact of CVE-2019-0768 extends beyond simple script execution bypass, as it enables attackers to perform a wide range of malicious activities including information disclosure, privilege escalation, and system compromise. Attackers can leverage this vulnerability to execute arbitrary code within the context of the victim's browser session, potentially leading to full system compromise if the user has elevated privileges. The vulnerability's persistence across different security contexts makes it particularly dangerous in targeted attacks where threat actors can craft specific payloads that exploit the bypass conditions to gain unauthorized access to sensitive data or system resources. This security feature bypass can be combined with other vulnerabilities to create more sophisticated attack chains, making it a valuable target for advanced persistent threat actors and cybercriminals seeking to establish persistent access to compromised systems.
Mitigation strategies for CVE-2019-0768 should focus on both immediate defensive measures and long-term architectural improvements to prevent similar vulnerabilities from occurring. Organizations should implement immediate patches from Microsoft that address the specific VBScript execution policy bypass conditions, while also considering browser hardening techniques such as disabling VBScript execution entirely in environments where it is not required. The vulnerability aligns with CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer and relates to ATT&CK technique T1059.005 for Windows Command Shell execution. Security teams should also implement network-based detection measures to monitor for suspicious VBScript execution patterns and consider deploying additional layers of protection such as application whitelisting, sandboxing, and comprehensive monitoring of browser-based script execution to identify potential exploitation attempts. The vulnerability underscores the importance of maintaining up-to-date security policies and regularly reviewing browser security configurations to prevent similar bypass scenarios from occurring in other components of the security infrastructure.