CVE-2025-54400 is a stack-based buffer overflow vulnerability identified in the Planet WGR-500 router firmware version v1.3411b190912. The vulnerability arises from improper handling of the 'counts' parameter in the formPingCmd functionality, which is used to compose a command string for executing a ping operation: "ping -c <counts> <ipaddr> 2>&1 > %s &". By sending a carefully crafted sequence of HTTP requests containing maliciously crafted 'counts' values, an attacker can 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 service. The vulnerability requires network access to the device’s HTTP interface and low privileges (PR:L), but no user interaction is needed. The CVSS 3.1 score of 8.8 reflects the vulnerability’s high impact on confidentiality, integrity, and availability, as successful exploitation could allow an attacker to take full control of the router, intercept or manipulate network traffic, or disrupt network services. No public exploits have been reported yet, but the vulnerability is publicly disclosed and considered critical. The lack of available patches at the time of disclosure necessitates immediate defensive measures to reduce exposure. The vulnerability is classified under CWE-121, indicating a classic stack-based buffer overflow issue due to unsafe string or buffer handling in the firmware code.

The impact of CVE-2025-54400 on European organizations can be significant, especially for those relying on Planet WGR-500 routers in their network infrastructure. Exploitation can lead to complete compromise of the affected router, allowing attackers to intercept, modify, or redirect network traffic, potentially leading to data breaches or espionage. The attacker could also disrupt network availability by causing device crashes or persistent denial of service. This is particularly concerning for critical infrastructure sectors such as energy, transportation, healthcare, and government agencies that depend on stable and secure network connectivity. The vulnerability’s ease of exploitation over the network without user interaction increases the risk of automated attacks or worm-like propagation within organizational networks. Additionally, compromised routers can serve as footholds for lateral movement or launching further attacks against internal systems. The absence of known exploits currently provides a small window for mitigation, but the high severity demands urgent attention to prevent future exploitation.

1. Immediately restrict access to the Planet WGR-500 management interface by limiting it to trusted internal networks or VPN connections only. 2. Implement network segmentation to isolate vulnerable devices from critical systems and sensitive data. 3. Monitor network traffic for unusual HTTP requests targeting the 'formPingCmd' functionality or suspicious command injection attempts. 4. Disable or restrict the ping command functionality on the router if configurable, to reduce attack surface. 5. Apply vendor-supplied firmware updates or patches as soon as they become available; regularly check Planet’s official channels for updates. 6. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting buffer overflow attempts against this router model. 7. Conduct regular security audits and vulnerability scans focused on network devices to identify unpatched or misconfigured equipment. 8. Educate network administrators about this vulnerability and enforce strict credential management to prevent privilege escalation. 9. Consider replacing affected devices with more secure alternatives if patches are delayed or unavailable.