CVE-1999-0790 in Communicator
Summary
by MITRE
A remote attacker can read information from a Netscape user's cache via JavaScript.
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Analysis
by VulDB Data Team • 04/21/2026
This vulnerability exists within the Netscape web browser implementation where JavaScript execution can potentially access cached data from users. The flaw stems from insufficient access controls between JavaScript code and the browser's cache mechanism, allowing malicious remote actors to exploit this weakness for information disclosure. The vulnerability represents a classic case of improper access control and cache manipulation that violates fundamental security principles governing web browser isolation.
The technical implementation of this vulnerability occurs when JavaScript code running in a web page can access cached resources from the user's browser cache. This typically happens through mechanisms that allow script execution to traverse cache memory structures or access cached objects through insecure API calls. The flaw leverages the fact that web browsers maintain cached versions of resources to improve performance, but these cached elements may not properly enforce access restrictions that separate different security contexts or origins. This type of vulnerability aligns with CWE-200 which describes improper exposure of sensitive information and CWE-284 which covers improper access control.
The operational impact of this vulnerability is significant as it allows remote attackers to potentially access sensitive information that users have previously visited or downloaded. This could include cached login credentials, personal data, financial information, or other confidential resources that were cached by the browser. Attackers could exploit this to perform reconnaissance, gather intelligence about users, or potentially escalate privileges within the browser environment. The vulnerability specifically targets the browser's cache management system, which is a critical component in maintaining user privacy and security.
Mitigation strategies for this vulnerability should focus on implementing proper access controls between JavaScript execution and cache mechanisms. Browser vendors should ensure that cached resources are properly isolated and that JavaScript cannot access cached data from other origins or security contexts. This includes implementing strict origin policies, proper cache invalidation mechanisms, and ensuring that cached data cannot be accessed through insecure scripting interfaces. Organizations should also consider implementing network-level protections and monitoring for suspicious cache access patterns. The remediation approach aligns with ATT&CK technique T1555 which covers credentials from password stores and T1083 which covers file and directory discovery. Additionally, this vulnerability highlights the importance of proper input validation and access control implementation in web applications and browser environments, as specified in security standards such as OWASP Top Ten and NIST cybersecurity frameworks.