CVE-1999-0809 in Communicator
Summary
by MITRE
Netscape Communicator 4.x with Javascript enabled does not warn a user of cookie settings, even if they have selected the option to "Only accept cookies originating from the same server as the page being viewed".
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Analysis
by VulDB Data Team • 04/19/2026
This vulnerability exists in netscape communicator version 4.x where the javascript engine fails to properly enforce cookie security settings configured by users. The flaw specifically affects the browser's cookie handling mechanism when javascript is enabled, creating a scenario where user preferences for cookie acceptance are ignored. When users select the option to only accept cookies from the originating server, the browser does not honor this setting during javascript execution, potentially allowing cross-site cookie injection attacks. This represents a significant security weakness in the browser's privacy protection mechanisms.
The technical implementation flaw stems from the javascript engine's inability to properly validate cookie sources during script execution. When javascript code attempts to set or access cookies, the browser should verify that these operations comply with the user's configured cookie policies. However, the vulnerability allows javascript to bypass these security checks, effectively rendering the user's cookie preference settings ineffective. This creates a scenario where malicious javascript code can set cookies from arbitrary domains regardless of the user's explicit security preferences.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential session hijacking and cross-site scripting attacks. Attackers can exploit this weakness by embedding malicious javascript code in web pages that sets cookies from third-party domains, effectively bypassing the user's intended security configuration. This allows for persistent tracking across different websites, session manipulation, and potential credential theft. The vulnerability is particularly dangerous because it operates silently without alerting users to the security breach, making it difficult to detect and investigate. This weakness directly violates the principle of least privilege in web security and undermines user trust in browser privacy controls.
Mitigation strategies should focus on immediate browser updates to address the javascript cookie handling flaw, along with implementing proper cookie security policies. Users should disable javascript when browsing untrusted websites or use browser extensions that enforce stricter cookie policies. Organizations should consider implementing content security policies and regular security audits to identify similar vulnerabilities in legacy browser configurations. This vulnerability aligns with CWE-284 Access Control Issues and maps to attack techniques in the ATT&CK framework under privilege escalation and credential access categories, specifically targeting the manipulation of browser security settings to gain unauthorized access to user sessions.