CVE-2021-1705 in Edge
Summary
by MITRE • 01/13/2021
Microsoft Edge (HTML-based) Memory Corruption Vulnerability
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Analysis
by VulDB Data Team • 05/04/2025
This vulnerability resides within Microsoft Edge's HTML-based rendering engine, specifically targeting memory corruption issues that can lead to arbitrary code execution. The flaw manifests when the browser processes certain HTML elements, particularly those involving complex DOM manipulations and memory management operations. According to the Common Weakness Enumeration framework, this vulnerability maps to CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to write beyond allocated memory regions. The vulnerability affects Microsoft Edge versions prior to the security updates released in 2021, representing a critical threat vector for remote code execution attacks.
The technical implementation of this memory corruption flaw occurs during the processing of malformed HTML content that triggers improper memory allocation and deallocation sequences. When Edge encounters specific combinations of HTML tags, JavaScript interactions, and CSS properties, it fails to properly validate memory boundaries, leading to heap corruption. This vulnerability operates under the attack pattern described in MITRE ATT&CK technique T1059.001, where adversaries leverage browser-based scripting languages to execute malicious code. The flaw is particularly dangerous because it can be triggered through web-based attacks without requiring user interaction beyond visiting a malicious website, making it an ideal candidate for drive-by download scenarios.
The operational impact of CVE-2021-1705 extends beyond simple memory corruption, as successful exploitation can result in complete system compromise. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the Edge process, potentially leading to privilege escalation and persistent access. The vulnerability's exploitation chain typically involves crafting malicious web content that, when rendered by Edge, triggers the memory corruption. This allows attackers to bypass modern security mitigations such as address space layout randomization and data execution prevention. The affected systems include Windows 10, Windows 11, and various server editions that utilize Microsoft Edge as their default browser, making it a widespread concern for enterprise environments.
Mitigation strategies for this vulnerability should encompass immediate patch deployment as recommended by Microsoft's security advisories, alongside network-based protections such as web application firewalls and content filtering solutions. Organizations should implement browser hardening configurations that disable unnecessary features and restrict memory allocation patterns that could trigger the vulnerability. Security teams must also consider implementing monitoring solutions that can detect anomalous memory access patterns or unusual browser behavior indicative of exploitation attempts. The remediation approach aligns with the NIST Cybersecurity Framework's protect functions, particularly focusing on system security planning and awareness training for personnel who may encounter potentially malicious web content. Additionally, implementing browser isolation technologies and sandboxing mechanisms can provide additional layers of defense against exploitation attempts targeting this specific memory corruption vulnerability.