CVE-1999-0071 in HTTP Server
Summary
by MITRE
apache httpd cookie buffer overflow for versions 1.1.1 and earlier.
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Analysis
by VulDB Data Team • 10/28/2025
The vulnerability identified as CVE-1999-0071 represents a critical buffer overflow flaw in the Apache HTTP Server software affecting versions 1.1.1 and earlier. This security weakness resides within the cookie handling mechanism of the web server, specifically in how it processes HTTP cookie headers sent by client browsers. The flaw occurs when the server receives a malformed cookie containing an excessive amount of data that exceeds the allocated buffer space, leading to potential memory corruption and arbitrary code execution. The vulnerability demonstrates a classic buffer overflow condition where insufficient input validation allows attackers to overwrite adjacent memory locations, potentially compromising the integrity and confidentiality of the affected system.
The technical implementation of this vulnerability stems from inadequate bounds checking within the Apache HTTPD server's cookie parsing routines. When processing HTTP cookie headers, the server fails to properly validate the length of cookie data before copying it into fixed-size buffers. This design flaw aligns with CWE-121, which categorizes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow scenarios. The flaw specifically manifests when the cookie data exceeds the predetermined buffer limits, causing a stack overflow that can be exploited to overwrite return addresses and execute malicious code with the privileges of the Apache process. Attackers can craft specially formatted cookie headers containing malicious payloads that trigger the overflow condition when processed by the vulnerable server instance.
The operational impact of CVE-1999-0071 extends beyond simple denial of service scenarios, as successful exploitation can result in complete system compromise. An attacker who successfully exploits this vulnerability gains the ability to execute arbitrary commands on the affected server, potentially leading to unauthorized access to sensitive data, privilege escalation, or even complete system takeover. The vulnerability affects web applications hosted on Apache servers, making it particularly dangerous for organizations relying on this widely deployed web server software. The attack surface is broad since cookies are standard HTTP headers used by virtually all web applications, and the exploitation can occur without requiring authentication or specialized knowledge of the target system. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1059 for command and script injection, and T1068 for local privilege escalation.
Mitigation strategies for CVE-1999-0071 primarily focus on immediate software updates and configuration hardening. Organizations should upgrade to Apache HTTP Server versions 1.2.0 or later, where the buffer overflow vulnerability has been addressed through proper input validation and bounds checking mechanisms. Additionally, implementing input validation at the application level can provide additional defense in depth, ensuring that cookie data is properly sanitized before processing. Network-level protections such as web application firewalls can help detect and block malicious cookie headers, though these measures are not foolproof against sophisticated attacks. System administrators should also consider implementing proper access controls and monitoring mechanisms to detect unusual cookie patterns that might indicate exploitation attempts. The vulnerability underscores the critical importance of keeping web server software updated and following secure coding practices that prevent buffer overflow conditions through proper memory management and input validation.