CVE-2024-5294 is a memory leak vulnerability classified under CWE-401, affecting the D-Link DIR-3040 router, specifically firmware version 120B03. The vulnerability exists in the prog.cgi program, which processes HNAP (Home Network Administration Protocol) requests via the lighttpd web server listening on HTTP and HTTPS ports (80 and 443). The flaw stems from improper handling of HTTP cookie values, where memory allocated during request processing is not properly released after its effective lifetime. This leads to a gradual consumption of system memory resources, which an attacker can exploit by sending crafted requests to the prog.cgi endpoint. Because the vulnerability does not require authentication or user interaction, an attacker positioned on the same network or within network adjacency can repeatedly trigger the memory leak, eventually causing the router to exhaust its memory and enter a denial-of-service state. This disrupts the router’s normal operation, potentially cutting off network access for connected devices. The vulnerability was assigned CVE-2024-5294 and has a CVSS v3.0 base score of 4.3, indicating a medium severity level. No public exploits have been reported yet, but the ease of exploitation and lack of authentication requirements make it a notable risk for affected deployments. The issue was reported by the Zero Day Initiative (ZDI) as ZDI-CAN-21668. No official patches or firmware updates have been linked yet, so mitigation relies on network controls and monitoring.

The primary impact of CVE-2024-5294 is a denial-of-service condition caused by memory exhaustion on affected D-Link DIR-3040 routers. This can lead to router crashes or severe performance degradation, resulting in network outages for all devices relying on the router for connectivity. Organizations using this router model in critical environments may experience disruption of business operations, loss of internet access, and potential secondary impacts on security monitoring or remote management capabilities. Since the vulnerability requires no authentication and can be exploited by network-adjacent attackers, it poses a risk in environments where untrusted users or devices share the same network segment, such as public Wi-Fi, enterprise guest networks, or poorly segmented internal networks. The lack of known exploits in the wild reduces immediate risk, but the vulnerability’s characteristics make it a candidate for future exploitation. The scope is limited to the specific router model and firmware version, but given D-Link’s global market presence, the impact can be widespread in affected deployments.

1. Monitor D-Link’s official channels for firmware updates addressing CVE-2024-5294 and apply patches promptly once available. 2. Implement network segmentation to isolate critical routers from untrusted or guest networks, reducing exposure to network-adjacent attackers. 3. Restrict access to router management interfaces (ports 80 and 443) using firewall rules or access control lists to trusted IP addresses only. 4. Employ intrusion detection/prevention systems (IDS/IPS) to monitor for unusual or repeated HNAP requests targeting prog.cgi endpoints, enabling early detection of exploitation attempts. 5. Regularly audit and update router firmware to the latest stable versions to minimize exposure to known vulnerabilities. 6. Consider deploying network-level rate limiting on HTTP/HTTPS traffic to the router to mitigate potential memory exhaustion from repeated requests. 7. In environments where the DIR-3040 is critical, evaluate alternative hardware or vendor solutions if timely patches are unavailable.