CVE-1999-0386 is a vulnerability affecting Microsoft Personal Web Server and FrontPage Personal Web Server version 4.0 on certain Windows systems. This vulnerability allows a remote attacker to read arbitrary files on the affected server by crafting and sending a nonstandard URL request. The flaw arises because the server improperly handles URL requests, enabling unauthorized file disclosure without requiring authentication. The vulnerability impacts confidentiality by exposing potentially sensitive files to unauthorized users. However, it does not allow modification or deletion of files (integrity unaffected) nor does it impact availability. The vulnerability was assigned a CVSS v2 base score of 5.0 (medium severity), reflecting its network accessibility, low attack complexity, no authentication requirement, and partial confidentiality impact. Microsoft released a patch in 1999 (MS99-010) to address this issue, which should be applied to affected systems to mitigate the risk. Although this vulnerability is over two decades old and no known exploits are currently active in the wild, legacy systems or environments still running these outdated servers remain at risk. The vulnerability primarily affects legacy Windows systems running FrontPage Personal Web Server 4.0, which was commonly used in the late 1990s and early 2000s for hosting personal or small business websites.

For European organizations, the primary impact of this vulnerability is unauthorized disclosure of sensitive information hosted on vulnerable servers. This could include configuration files, source code, or other data that could aid further attacks or lead to data breaches. While modern organizations are unlikely to use such outdated software, certain small businesses, educational institutions, or legacy systems in government or industrial environments might still be running these servers, especially in less digitally modernized regions. Exposure of confidential information could lead to reputational damage, regulatory non-compliance (e.g., GDPR violations if personal data is exposed), and potential follow-on attacks leveraging disclosed information. The lack of integrity or availability impact limits the scope of damage, but confidentiality breaches remain a serious concern. Given the age of the vulnerability, the risk is mostly relevant to organizations with legacy infrastructure that has not been updated or decommissioned.

1. Immediate application of the official Microsoft patch MS99-010 to all affected systems is the primary mitigation step. 2. Identify and inventory any legacy systems running Microsoft Personal Web Server or FrontPage Personal Web Server 4.0, and plan for their upgrade or decommissioning. 3. If patching or upgrading is not feasible, isolate these legacy servers from the internet and restrict access using network segmentation and firewall rules to trusted internal users only. 4. Implement strict monitoring and logging on these servers to detect any suspicious URL requests or file access attempts. 5. Conduct regular security audits to identify outdated software and ensure compliance with current security standards. 6. Educate IT staff about the risks of running unsupported legacy software and the importance of timely patching and system upgrades. 7. Consider migrating to modern, supported web server platforms that receive regular security updates and support secure configurations.