CVE-2025-56241 is a critical vulnerability discovered in the Aztech DSL5005EN router firmware version 1.00.AZ_2013-05-10 and possibly other versions. The vulnerability resides in the sysAccess.asp endpoint, which improperly handles POST requests that allow unauthenticated attackers to change the administrator password. This bypasses all authentication mechanisms, granting attackers full administrative privileges on the device. The vulnerability is classified under CWE-284 (Improper Access Control), indicating a failure to enforce proper access restrictions. The CVSS v3.1 base score is 7.5 (High), with attack vector Network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no confidentiality or integrity impact (C:N/I:N), but high impact on availability (A:H). This means attackers can disrupt network availability by locking out legitimate administrators or modifying router configurations. The vulnerability is exploitable remotely without authentication or user interaction, making it highly dangerous in exposed network environments. No official patches or firmware updates have been published yet, and no known exploits have been observed in the wild. However, the potential for exploitation is significant due to the simplicity of the attack vector and the critical role routers play in network infrastructure.

For European organizations, this vulnerability could lead to severe network disruptions by allowing attackers to gain full administrative control over affected routers. This could result in denial of service by locking out legitimate administrators, altering network configurations, or redirecting traffic for interception or further attacks. Organizations relying on Aztech DSL5005EN routers in critical infrastructure, small to medium enterprises, or home office environments are particularly vulnerable. The compromise of router administrative credentials can also facilitate lateral movement within internal networks, increasing the risk of broader compromise. Given the lack of patches, the threat to availability and operational continuity is significant. Additionally, attackers could use compromised routers as footholds for launching attacks against European networks or exfiltrating sensitive data. The impact is heightened in sectors where network uptime and security are critical, such as finance, healthcare, and government services.

Since no official patches or firmware updates are currently available, European organizations should implement immediate compensating controls. These include disabling remote management interfaces on affected routers to prevent external exploitation. Network segmentation should be enforced to isolate vulnerable routers from critical internal systems. Replace or upgrade affected devices with models from vendors providing timely security updates. Monitor network traffic for unusual POST requests targeting sysAccess.asp or other suspicious administrative access attempts. Employ strong perimeter defenses such as firewalls and intrusion detection/prevention systems to block unauthorized access to router management interfaces. Regularly audit router configurations and change default credentials where possible. Educate IT staff about this vulnerability to ensure rapid response if exploitation attempts are detected. Finally, maintain an inventory of all Aztech DSL5005EN routers in use to prioritize mitigation efforts.