CVE-2025-54399 is a stack-based buffer overflow vulnerability identified in the Planet WGR-500 router firmware version v1.3411b190912. The flaw exists in the formPingCmd functionality, which processes HTTP requests containing an 'ipaddr' parameter used to construct a shell command string for ping operations: "ping -c <counts> <ipaddr> 2>&1 > %s &". Due to insufficient input validation and improper bounds checking on the 'ipaddr' parameter, an attacker can craft a series of HTTP requests that overflow the stack buffer. This overflow can overwrite the return address or other control data on the stack, enabling arbitrary code execution with the privileges of the affected process. The vulnerability requires only low privileges (PR:L) and no user interaction (UI:N), making it remotely exploitable over the network (AV:N). The impact includes full compromise of confidentiality, integrity, and availability of the device, potentially allowing attackers to execute arbitrary commands, disrupt network operations, or pivot into internal networks. Despite no known exploits currently in the wild, the vulnerability is critical due to the ease of exploitation and the widespread use of the affected device in network environments. No official patches have been linked yet, increasing the urgency for mitigations.

For European organizations, the exploitation of CVE-2025-54399 could lead to severe consequences. Compromise of Planet WGR-500 routers can result in unauthorized access to internal networks, interception or manipulation of sensitive data, disruption of network services, and potential lateral movement to other critical systems. This is particularly concerning for sectors relying on these routers for secure communications, such as government agencies, telecommunications providers, and critical infrastructure operators. The high CVSS score reflects the potential for complete device takeover without user interaction, which could facilitate espionage, sabotage, or ransomware deployment. The absence of known exploits currently provides a window for proactive defense, but the vulnerability’s nature suggests attackers may develop exploits rapidly. Organizations with these devices in their network perimeter or internal segments face elevated risk, especially if remote management interfaces are exposed.

1. Immediate mitigation should include restricting access to the management interface of Planet WGR-500 devices to trusted networks only, using network segmentation and firewall rules. 2. Disable or restrict the vulnerable formPingCmd functionality if possible through device configuration. 3. Monitor network traffic for unusual HTTP requests targeting the 'ipaddr' parameter or abnormal ping command patterns. 4. Implement intrusion detection/prevention systems (IDS/IPS) signatures tailored to detect exploitation attempts of this buffer overflow. 5. Regularly audit and inventory network devices to identify all Planet WGR-500 routers and verify firmware versions. 6. Engage with the vendor for firmware updates or patches; if unavailable, consider replacing affected devices with more secure alternatives. 7. Employ network-level anomaly detection to identify potential post-exploitation activities. 8. Enforce strict access controls and multi-factor authentication on device management interfaces to limit attacker foothold. 9. Conduct employee awareness training to recognize signs of network compromise related to device exploitation.