CVE-1999-0071 is a high-severity buffer overflow vulnerability affecting Apache HTTP Server versions 1.1.1 and earlier. The vulnerability arises from improper handling of HTTP cookies, where the server fails to adequately validate the size of cookie data before copying it into a fixed-size buffer. This unchecked buffer copying can lead to a buffer overflow condition, allowing an attacker to overwrite adjacent memory. Exploiting this flaw could enable remote attackers to execute arbitrary code on the affected server, potentially leading to full system compromise. The vulnerability is remotely exploitable over the network without requiring authentication or user interaction, making it particularly dangerous. Given the age of the affected versions (published in 1997), this vulnerability primarily concerns legacy systems that have not been updated or replaced. No official patches are available for these versions, and no known exploits have been observed in the wild, likely due to the obsolescence of the affected software versions. However, the underlying risk remains significant if such outdated systems are still in operation.

For European organizations, the impact of this vulnerability depends largely on whether legacy Apache HTTP Server 1.1.1 or earlier versions are still in use. If so, exploitation could lead to unauthorized disclosure of sensitive information (confidentiality impact), unauthorized modification of data or server behavior (integrity impact), and denial of service or full system takeover (availability impact). Given the critical role of web servers in organizational IT infrastructure, successful exploitation could disrupt business operations, damage reputation, and lead to regulatory non-compliance under GDPR if personal data is compromised. Although modern Apache versions have long since replaced these vulnerable versions, some industrial control systems, embedded devices, or legacy applications in European organizations might still run outdated software, posing a risk. The lack of patches means organizations must rely on mitigation strategies other than software updates.

Since no patches are available for Apache HTTP Server 1.1.1 and earlier, organizations should prioritize upgrading to the latest supported Apache HTTP Server versions that have addressed this and other vulnerabilities. If upgrading is not immediately feasible, organizations should implement network-level protections such as web application firewalls (WAFs) configured to detect and block anomalous or oversized cookie headers. Additionally, restricting external access to legacy servers via network segmentation and strict firewall rules can reduce exposure. Regularly auditing infrastructure to identify and inventory legacy Apache servers is critical. Where legacy systems must remain operational, consider deploying intrusion detection/prevention systems (IDS/IPS) with signatures targeting buffer overflow attempts. Finally, organizations should plan for decommissioning or replacing legacy systems to eliminate this and other security risks.