CVE-2014-2139 in ONS 15454
Summary
by MITRE
Cisco ONS 15454 controller cards with software 9.6 and earlier allow remote attackers to cause a denial of service (flash write outage) via a TCP FIN attack that triggers file-descriptor exhaustion, aka Bug ID CSCug97315.
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Analysis
by VulDB Data Team • 05/10/2026
The vulnerability described in CVE-2014-2139 represents a critical denial of service weakness affecting Cisco ONS 15454 controller cards operating with software versions 9.6 and earlier. This flaw exists within the network infrastructure equipment that manages optical transport networks, specifically targeting the controller card functionality that handles communication protocols and system operations. The vulnerability demonstrates how even sophisticated networking hardware can contain fundamental design flaws that expose operational systems to remote exploitation, potentially disrupting critical telecommunications services.
The technical mechanism behind this vulnerability involves a specific TCP FIN attack pattern that exploits file descriptor management within the controller card's operating system. When remote attackers send carefully crafted TCP FIN packets to the affected system, the controller card's software fails to properly manage its file descriptor resources, leading to exhaustion of available descriptors. This occurs because the system does not adequately handle the termination of TCP connections in a way that prevents resource leakage, causing the flash storage write operations to fail and ultimately resulting in a complete denial of service condition. The vulnerability is particularly dangerous because it can be triggered remotely without requiring authentication, making it accessible to any attacker with network access to the affected equipment.
The operational impact of this vulnerability extends far beyond simple service disruption, as it can compromise the reliability of entire optical transport networks that depend on these controller cards for proper operation. When flash write operations fail due to file descriptor exhaustion, the controller cards cannot properly maintain their configuration data, system logs, or operational parameters, leading to cascading failures that may require manual intervention to restore normal operations. Network operators face significant challenges when this vulnerability is exploited, as the denial of service affects not just individual devices but can potentially disrupt large segments of their transport infrastructure, especially in environments where multiple controller cards operate in concert to manage complex network topologies.
Organizations should implement immediate mitigations including network segmentation to isolate affected controller cards from untrusted networks, deployment of access control lists to filter TCP FIN packets, and regular monitoring for unusual connection termination patterns. The vulnerability aligns with CWE-400, which categorizes the issue as an uncontrolled resource consumption problem, and relates to ATT&CK technique T1499.004, which describes network denial of service attacks. Additionally, Cisco recommends upgrading to software versions that address this specific flaw, as well as implementing network intrusion detection systems that can identify and alert on suspicious TCP FIN patterns. The remediation process requires careful planning to avoid service disruption during the upgrade phase, particularly in mission-critical environments where network availability is paramount.