CVE-1999-1237 in HTTP Server
Summary
by MITRE
Multiple buffer overflows in smbvalid/smbval SMB authentication library, as used in Apache::AuthenSmb and possibly other modules, allows remote attackers to execute arbitrary commands via (1) a long username, (2) a long password, and (3) other unspecified methods.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability described in CVE-1999-1237 represents a critical security flaw within the smbvalid/smbval SMB authentication library that was widely utilized in web server authentication modules including Apache::AuthenSmb. This issue stems from improper input validation mechanisms within the SMB authentication framework that fails to adequately sanitize user-provided credentials before processing them. The vulnerability manifests as multiple buffer overflow conditions that occur when the library receives excessively long authentication parameters, creating opportunities for malicious exploitation that can compromise the underlying system. The affected library's design lacks proper bounds checking mechanisms, allowing attackers to overwrite adjacent memory locations with crafted input data. These buffer overflows specifically occur during the handling of username and password parameters, with additional unspecified methods contributing to the overall vulnerability surface. The impact extends beyond simple authentication bypasses, as the memory corruption can be leveraged to execute arbitrary code with the privileges of the affected service. This vulnerability directly relates to CWE-121 which describes stack-based buffer overflow conditions, and CWE-122 which addresses heap-based buffer overflows, both of which are fundamental weaknesses in memory management that enable privilege escalation and arbitrary code execution. The attack vector is particularly concerning as it allows remote exploitation without requiring authentication, making it accessible to any attacker who can reach the vulnerable service.
The technical implementation of this vulnerability exploits the fundamental flaw in how the smbvalid/smbval library processes authentication requests. When legitimate users submit credentials, the library allocates fixed-size buffers to store these values without proper validation of input length. An attacker can craft maliciously long username or password strings that exceed the allocated buffer boundaries, causing data to spill into adjacent memory regions. This overflow can overwrite critical program variables, return addresses, or function pointers, which when carefully manipulated can redirect program execution flow to malicious code. The specific mechanisms by which the overflow occurs align with the ATT&CK framework's T1059.007 technique for command and script injection, where attackers leverage buffer overflows to inject and execute arbitrary commands. The vulnerability's exploitation requires precise understanding of the memory layout and can be enhanced through techniques such as return-oriented programming or direct code injection. The fact that this affects multiple methods of authentication input increases the attack surface significantly, as different code paths may be susceptible to similar overflow conditions. The lack of input sanitization makes this vulnerability particularly dangerous in web environments where user input is inherently untrusted and can be easily manipulated through HTTP requests or other network protocols.
The operational impact of CVE-1999-1237 extends far beyond simple service disruption, as successful exploitation can result in complete system compromise. Organizations running web servers with vulnerable authentication modules face potential data breaches, unauthorized access to sensitive resources, and possible lateral movement within their network infrastructure. The vulnerability's remote exploitability means that attackers can target systems from anywhere on the internet without requiring physical access or prior authentication credentials. This creates a significant risk for enterprise environments where web applications may be exposed to public networks, potentially allowing attackers to gain access to internal systems that would otherwise be protected by network segmentation. The compromised system can be used as a foothold for further attacks, including credential theft, data exfiltration, or deployment of additional malware. Organizations may also face regulatory compliance issues if sensitive data is accessed or compromised through this vulnerability, as many compliance frameworks require protection against known vulnerabilities. The widespread use of Apache::AuthenSmb and similar modules in enterprise environments means that a single vulnerable installation can represent a significant risk to an entire organization's security posture. Additionally, the vulnerability's presence in authentication libraries means that successful exploitation can provide attackers with elevated privileges, potentially allowing them to access administrative functions or modify critical system configurations.
Mitigation strategies for CVE-1999-1237 require immediate attention and comprehensive approach across all affected systems. Organizations should prioritize patching or upgrading to versions of the smbvalid/smbval library that implement proper input validation and buffer management techniques. The most effective immediate solution involves replacing vulnerable authentication modules with secure alternatives that properly validate input lengths and implement robust memory management practices. System administrators should also implement network segmentation to limit access to vulnerable services and deploy intrusion detection systems that can identify suspicious authentication attempts. Input validation should be implemented at multiple layers including web application firewalls, proxy servers, and application-level controls to provide defense in depth. Regular security assessments should be conducted to identify other potentially vulnerable components within the authentication infrastructure, as similar buffer overflow vulnerabilities may exist in other parts of the system. Organizations should also implement monitoring for unusual authentication patterns that might indicate exploitation attempts, including unusually long authentication parameters or repeated failed authentication attempts. The implementation of secure coding practices and regular security training for development teams can help prevent similar vulnerabilities from being introduced in future code implementations. Additionally, maintaining up-to-date vulnerability databases and automated patch management systems can help ensure that known vulnerabilities like CVE-1999-1237 are addressed promptly across all systems. Regular penetration testing and vulnerability scanning should be performed to identify any remaining instances of the vulnerable library or related components that may not have been updated.