CVE-2018-0840 in Edge
Summary
by MITRE
Internet Explorer in Microsoft Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8.1 and Windows RT 8.1, Windows Server 2012 and R2, and Internet Explorer and Microsoft Edge in Windows 10 Gold, 1511, 1607, 1703, 1709, and Windows Server 2016 allows remote code execution, due to how the scripting engine handles objects in memory, aka "Scripting Engine Memory Corruption Vulnerability". This CVE ID is unique from CVE-2018-0834, CVE-2018-0835, CVE-2018-0836, CVE-2018-0837, CVE-2018-0838, CVE-2018-0856, CVE-2018-0857, CVE-2018-0858, CVE-2018-0859, CVE-2018-0860, CVE-2018-0861, and CVE-2018-0866.
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Analysis
by VulDB Data Team • 09/10/2025
The vulnerability identified as CVE-2018-0840 represents a critical memory corruption flaw within Microsoft's scripting engine that affects multiple versions of Internet Explorer and Microsoft Edge across various Windows operating systems. This vulnerability specifically targets the handling of objects in memory during script execution, creating a pathway for remote code execution attacks that can be exploited by malicious actors without user interaction. The flaw exists in the way the scripting engine manages memory allocation and object references, particularly when processing certain JavaScript or VBScript code within web browsers.
The technical nature of this vulnerability falls under the Common Weakness Enumeration category CWE-125, which describes "Out-of-bounds Read" conditions that can occur when software reads data from memory locations outside the intended boundaries of allocated buffers. The scripting engine's memory management system fails to properly validate object references and memory boundaries during dynamic script execution, allowing attackers to manipulate memory contents through crafted malicious code. This memory corruption can lead to arbitrary code execution with the privileges of the current user, potentially enabling full system compromise when combined with other exploitation techniques.
From an operational perspective, this vulnerability poses significant risk to organizations as it affects widely deployed browser software across multiple Windows versions including legacy systems. The vulnerability is particularly dangerous because it can be triggered through web browsing activities without any user interaction, making it an ideal candidate for drive-by download attacks. Attackers can host malicious websites that automatically exploit this vulnerability when users visit them, bypassing traditional security measures such as user awareness training or manual browser configuration. The impact extends beyond individual user devices to potentially compromise entire network infrastructures, especially in environments where users have administrative privileges.
Security practitioners should implement multiple layers of defense to mitigate this vulnerability, including immediate patch deployment for all affected systems, browser hardening configurations, and network-based protections such as web application firewalls. The mitigation strategy should align with ATT&CK framework techniques for defending against remote code execution, particularly focusing on mitigating the initial access vectors through web-based attacks. Organizations should also consider implementing browser isolation technologies and restricting internet access for critical systems to reduce exposure. Regular security assessments and vulnerability scanning should be conducted to identify any unpatched systems, while incident response procedures should be updated to include specific protocols for handling memory corruption vulnerabilities. The vulnerability's exploitation potential makes it a high-priority target for both nation-state actors and criminal organizations, emphasizing the need for proactive security measures.