CVE-2025-69674: CDATA FD614GS3 Buffer Overflow Flaw

CVE-2025-69674 Overview

A Buffer Overflow vulnerability has been identified in the CDATA FD614GS3-R850 V3 firmware that allows attackers to execute arbitrary code. The vulnerability exists in the mesh_node_config and domiainblk_config modules, specifically affecting the node_mac, node_opt, opt_param, and domainblk parameters. Successful exploitation of this vulnerability could allow an attacker to gain complete control over the affected network device.

Critical Impact

This buffer overflow vulnerability enables arbitrary code execution on CDATA FD614GS3-R850 network devices, potentially allowing attackers to compromise network infrastructure and establish persistent access.

Affected Products

• CDATA FD614GS3-R850 V3.2.7_P161006 (Build.0333.250211)

Discovery Timeline

• 2026-02-19 - CVE CVE-2025-69674 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2025-69674

Vulnerability Analysis

This buffer overflow vulnerability affects the CDATA FD614GS3-R850 firmware, an optical network terminal (ONT) device commonly deployed in telecommunications infrastructure. The vulnerability resides in the web management interface modules responsible for mesh node configuration and domain blocking functionality.

When processing user-supplied input through the node_mac, node_opt, opt_param, and domainblk parameters, the affected modules fail to properly validate the length of the input data before copying it into fixed-size memory buffers. This lack of bounds checking allows an attacker to overflow the allocated buffer space, potentially overwriting adjacent memory regions including return addresses and function pointers.

The vulnerability affects firmware version V3.2.7_P161006 (Build.0333.250211). Given that the vulnerable parameters are part of configuration modules accessible through the device's management interface, exploitation may require authenticated access depending on the device's access control configuration.

Root Cause

The root cause of this vulnerability is improper input validation and insufficient boundary checking in the mesh_node_config and domiainblk_config modules. When handling the node_mac, node_opt, opt_param, and domainblk parameters, the firmware fails to verify that user-supplied data does not exceed the size of the destination buffer. This classic buffer overflow condition allows memory corruption when overly long input values are submitted to the vulnerable endpoints.

Attack Vector

An attacker can exploit this vulnerability by sending specially crafted requests to the device's web management interface with maliciously oversized values for the vulnerable parameters. The attack flow typically involves:

1. Identifying a target CDATA FD614GS3-R850 device running the vulnerable firmware version
2. Accessing the web management interface (authentication may be required)
3. Submitting crafted input containing overflow payloads to the mesh_node_config or domiainblk_config modules
4. Overwriting memory to redirect execution flow or inject malicious code
5. Achieving arbitrary code execution with the privileges of the web service process

The vulnerability allows an attacker to execute arbitrary code on the affected device, potentially leading to complete device compromise, network traffic interception, or use of the device as a pivot point for further network intrusion.

For technical details regarding this vulnerability, refer to the GitHub Gist Security Insights published by the security researcher.

Detection Methods for CVE-2025-69674

Indicators of Compromise

• Unusual or unexpected web requests to mesh_node_config or domiainblk_config endpoints containing excessively long parameter values
• Abnormal process crashes or restarts on CDATA FD614GS3-R850 devices
• Unexpected network connections originating from ONT devices to external IP addresses
• Evidence of firmware modifications or unauthorized configuration changes

Detection Strategies

• Implement network intrusion detection rules to identify HTTP requests with abnormally long node_mac, node_opt, opt_param, or domainblk parameter values targeting CDATA devices
• Monitor device logs for repeated crashes or service restarts that may indicate exploitation attempts
• Deploy web application firewall (WAF) rules to filter requests with oversized parameters to device management interfaces

Monitoring Recommendations

• Enable comprehensive logging on CDATA FD614GS3-R850 devices and forward logs to a centralized SIEM solution
• Establish baseline behavior for device management interface access and alert on anomalies
• Conduct periodic firmware integrity checks to detect unauthorized modifications
• Monitor network traffic for unusual outbound connections from network infrastructure devices

How to Mitigate CVE-2025-69674

Immediate Actions Required

• Restrict access to the device management interface to trusted administrative networks only using firewall rules or access control lists
• Implement strong authentication for all administrative access to CDATA devices
• Segment network infrastructure devices from general network traffic to limit attack surface
• Review device logs for evidence of exploitation attempts

Patch Information

At the time of this publication, no vendor patch information is available for this vulnerability. Organizations should monitor the CDATatec Product Information page for firmware updates that address this vulnerability.

Workarounds

• Implement network-level access controls to restrict management interface access to authorized IP addresses only
• Deploy a web application firewall or reverse proxy in front of the device management interface to filter malicious requests
• Consider disabling unused features including mesh node configuration if not required for operations
• Use out-of-band management networks for device administration where possible

# Example: Restrict management access using iptables on an upstream firewall
# Allow management access only from trusted admin network
iptables -A FORWARD -d <DEVICE_IP> -p tcp --dport 80 -s <ADMIN_NETWORK>/24 -j ACCEPT
iptables -A FORWARD -d <DEVICE_IP> -p tcp --dport 443 -s <ADMIN_NETWORK>/24 -j ACCEPT
iptables -A FORWARD -d <DEVICE_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <DEVICE_IP> -p tcp --dport 443 -j DROP