CVE-1999-0827 in Internet Explorer
Summary
by MITRE
By default, Internet Explorer 5.0 and other versions enables the "Navigate sub-frames across different domains" option, which allows frame spoofing.
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Analysis
by VulDB Data Team • 04/19/2026
This vulnerability exists in internet explorer versions 5.0 and earlier where the default security settings permit cross-domain frame navigation. The flaw stems from the browser's handling of frame elements and how it manages navigation between different domains within framed web pages. When the "Navigate sub-frames across different domains" option is enabled, malicious actors can exploit this behavior to load content from unauthorized domains into frames within a victim's browser session, creating opportunities for frame spoofing attacks.
The technical implementation of this vulnerability involves the browser's frame navigation mechanisms that do not properly enforce cross-origin restrictions. When a web page contains frames that load content from different domains, the default configuration allows these frames to navigate to arbitrary locations without proper security boundaries. This creates a path for attackers to manipulate frame content and potentially redirect users to malicious sites while maintaining the appearance of legitimate web content. The vulnerability is particularly dangerous because it operates at the browser level rather than the application level, making it difficult to detect through traditional application security measures.
The operational impact of this vulnerability extends beyond simple frame spoofing to encompass broader security implications including man-in-the-middle attacks, phishing attempts, and session hijacking. Attackers can leverage this flaw to create convincing fake web pages that appear legitimate while redirecting users to malicious destinations. The vulnerability affects users who browse the internet with default security settings, making it particularly dangerous as it requires no specialized knowledge or tools to exploit. This makes it a significant concern for organizations where users may not be security-aware or where default browser configurations are not properly hardened.
Organizations should immediately disable the problematic frame navigation option in affected browsers and implement comprehensive browser security policies. The mitigation strategy should include updating to supported browser versions that properly enforce cross-origin restrictions and implementing security headers such as Content Security Policy to prevent unauthorized frame loading. This vulnerability aligns with CWE-16 Configuration and CWE-94 Code Injection categories, while also mapping to ATT&CK techniques related to credential access and defense evasion through web-based attacks. Regular security awareness training for users and proper browser hardening procedures should be implemented to prevent exploitation of this and similar configuration-based vulnerabilities.