ASUS has released new firmware for several DSL series routers to address a critical authentication bypass vulnerability that could allow remote attackers to take over affected devices without valid credentials. The flaw is tracked as CVE-2025-59367 and has been assigned a CVSS v4.0 score of 9.3 in the National Vulnerability Database, placing it in the highest severity category.
According to ASUS and public vulnerability records, the issue affects at least three consumer models in the DSL family: DSL N16, DSL AC750, and DSL AC51. An authentication bypass in the web management interface can enable unauthorized access to the router’s administrative functions when the device is reachable from the internet. The attacks are described as low complexity and do not require user interaction, which significantly increases the practical risk where the management interface is exposed.
Security researchers and vendors tracking the flaw have warned that a large number of susceptible devices may already be visible on the public internet. A scan result shared by one researcher using the FOFA search platform indicated more than fifty thousand potentially exposed routers that appeared to match vulnerable fingerprints, although that figure does not confirm how many are actually exploitable.
ASUS has published updated firmware for the affected models and is advising customers to apply the patches as soon as possible. The company’s security advisory instructs administrators to consult the Security Update for DSL Series Router section for model-specific firmware versions and additional guidance. In parallel, security vendors are updating detection plugins and device inventories so that enterprise vulnerability management tools can automatically flag the impacted hardware.
For CISOs and network security teams, the incident underscores several recurring themes in consumer-grade networking equipment deployed in small offices and home offices. Devices originally procured for residential use often persist in production environments with default configurations and remote management enabled, while patching and lifecycle management lag behind corporate standards. Where DSL routers or similar appliances provide primary connectivity for branch or home workers, they effectively become unmanaged external perimeter devices.
In the short term, organizations are being urged to identify any use of the affected ASUS models and to prioritize firmware upgrades. Where upgrades cannot be applied immediately, security teams should ensure that web administration interfaces are not exposed to the internet, restrict access to management functions to trusted internal networks or VPNs, and monitor for anomalous configuration changes on DSL gateways. Over the longer term, the vulnerability will likely reinforce the case for tighter policies around consumer-grade hardware, and for treating home routers as an extension of the enterprise attack surface rather than benign edge devices.
Sources: ASUS Security Advisory, NVD CVE-2025-59367, BleepingComputer
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By the ID Tech Editorial Team
