CVE-2024-0531 is a critical security vulnerability identified in the Tenda A15 router, specifically version 15.13.07.13. The flaw exists in the web-based management interface component, within the /goform/setBlackRule endpoint. The vulnerability is a stack-based buffer overflow (CWE-121) triggered by improper handling of the 'deviceList' parameter. An attacker can remotely send a specially crafted request to this endpoint, causing the buffer overflow condition. This can lead to arbitrary code execution, allowing the attacker to compromise the device's confidentiality, integrity, and availability. The vulnerability requires no user interaction but does require high privileges (PR:H) to exploit, indicating that some form of authentication or elevated access is necessary. The CVSS v3.1 score is 7.2 (high), reflecting the significant impact on confidentiality, integrity, and availability, combined with network attack vector and low attack complexity. The vendor, Tenda, was contacted but has not responded or provided a patch, leaving affected devices exposed. Although no public exploits are currently known in the wild, the vulnerability details have been disclosed, increasing the risk of exploitation by threat actors. The lack of a patch and public exploit availability means that organizations using this router version remain vulnerable and must take immediate mitigation steps to protect their networks.

For European organizations, the impact of this vulnerability can be severe. The Tenda A15 router is commonly used in small to medium-sized enterprises and residential environments, often serving as a gateway device. Successful exploitation could allow attackers to execute arbitrary code remotely, potentially leading to full device compromise. This could enable attackers to intercept or manipulate network traffic, launch further attacks within the internal network, or disrupt network availability. Confidential information passing through the router could be exposed or altered, impacting data privacy and regulatory compliance such as GDPR. The requirement for high privileges to exploit suggests that attackers may need to first gain some level of access, but once achieved, the consequences are critical. The absence of vendor response and patch availability increases the risk for organizations relying on this hardware. Disruption or compromise of network infrastructure devices like routers can have cascading effects on business operations, especially for organizations with remote offices or teleworking setups dependent on these devices.

1. Immediate network segmentation: Isolate Tenda A15 devices from critical infrastructure and sensitive data networks to limit potential lateral movement if compromised. 2. Restrict management interface access: Limit access to the web-based management interface to trusted IP addresses and use VPNs or secure channels for administrative access. 3. Monitor network traffic: Deploy intrusion detection/prevention systems (IDS/IPS) to detect anomalous requests targeting /goform/setBlackRule or unusual traffic patterns from Tenda A15 devices. 4. Replace or upgrade hardware: Where possible, replace affected Tenda A15 routers with devices from vendors with active security support and patch management. 5. Implement strong authentication: Ensure that router management interfaces use strong, unique credentials and consider multi-factor authentication if supported. 6. Regularly audit device firmware versions and configurations to identify and remediate vulnerable devices promptly. 7. Apply network-level filtering to block suspicious payloads or malformed requests targeting the vulnerable endpoint. 8. Stay informed on vendor updates or community patches and apply them immediately once available.