CVE-1999-1149 in CSM
Summary
by MITRE
Buffer overflow in CSM Proxy 4.1 allows remote attackers to cause a denial of service (crash) via a long string to the FTP port.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability identified as CVE-1999-1149 represents a critical buffer overflow flaw within the CSM Proxy 4.1 software implementation that specifically affects the FTP service component. This type of vulnerability falls under the broader category of software defects that can lead to unpredictable behavior and system instability. The CSM Proxy application serves as a network proxy solution that facilitates communication between clients and servers, with the FTP port functionality being particularly susceptible to exploitation due to inadequate input validation mechanisms. The flaw manifests when the system receives a malformed input string that exceeds the allocated buffer space, causing the application to overwrite adjacent memory segments and ultimately resulting in application termination.
The technical nature of this buffer overflow vulnerability stems from the proxy software's failure to properly validate the length of incoming data streams directed to the FTP service port. When an attacker submits a specially crafted long string to the FTP port, the application attempts to store this data in a predetermined memory buffer without sufficient bounds checking. This lack of input sanitization creates an exploitable condition where the excessive data overflows the allocated buffer space and begins writing into adjacent memory locations, potentially corrupting critical program data structures or execution pointers. The vulnerability is classified as a classic stack-based buffer overflow according to CWE-121, which specifically addresses violations of the stack buffer overflow category. This type of flaw is particularly dangerous as it can be leveraged to cause arbitrary code execution or system crashes, though in this instance the primary impact is limited to denial of service.
The operational impact of CVE-1999-1149 extends beyond simple service disruption, as it represents a fundamental security weakness that could be exploited by malicious actors to compromise network availability. Organizations relying on CSM Proxy 4.1 for their FTP proxy services face significant risk of service interruptions that could impact business operations and user access to network resources. The remote nature of the attack means that adversaries need not have physical access to the system, allowing them to exploit the vulnerability from anywhere on the network. This vulnerability directly aligns with the attack pattern described in the MITRE ATT&CK framework under the T1499 category, specifically targeting network service availability through the manipulation of service protocols. The flaw demonstrates how seemingly innocuous protocol handling can create substantial security risks when proper input validation is omitted, particularly in network services that process untrusted data from external sources.
Mitigation strategies for this vulnerability should prioritize immediate patching of the CSM Proxy 4.1 software to address the buffer overflow condition through proper input validation and bounds checking mechanisms. Organizations should implement network segmentation and access controls to limit exposure of vulnerable FTP proxy services to untrusted networks, utilizing firewall rules to restrict access to the affected port. The implementation of intrusion detection systems can help identify potential exploitation attempts by monitoring for unusually long data packets being transmitted to the FTP service port. Additionally, network administrators should consider implementing application-level firewalls or proxy solutions that provide additional input validation layers between the network edge and vulnerable services. Regular vulnerability assessments and security audits should be conducted to identify similar buffer overflow conditions in other network services and applications, as this represents a common class of vulnerability that has been documented across numerous software platforms throughout the history of network security. The remediation process should also include thorough testing of patched applications to ensure that the fix does not introduce new operational issues while effectively addressing the memory corruption vulnerability.