CVE-2025-11325 is a stack-based buffer overflow vulnerability identified in the Tenda AC18 router firmware version 15.03.05.19(6318). The vulnerability resides in an unknown functionality related to the /goform/fast_setting_pppoe_set endpoint, specifically in the handling of the Username argument. By crafting a malicious request with a specially manipulated Username parameter, an attacker can overflow the stack buffer remotely, without requiring authentication or user interaction. This buffer overflow can potentially allow an attacker to execute arbitrary code on the device, leading to full compromise of the router. The vulnerability has a CVSS 4.0 base score of 8.7, indicating high severity, with attack vector being network-based, low attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Although no confirmed exploits in the wild have been reported, a public exploit is available, increasing the likelihood of exploitation. The vulnerability affects only the specified firmware version, and no official patches have been linked yet. The router’s exposure to the internet and use in enterprise or home networks makes this a critical security concern.

The impact of CVE-2025-11325 on European organizations can be significant. Successful exploitation could allow attackers to gain remote code execution on Tenda AC18 routers, leading to full device compromise. This can result in interception or manipulation of network traffic, disruption of internet connectivity, and potential pivoting into internal networks. Confidential data passing through the router could be exposed or altered, undermining data integrity and privacy. Availability of network services could be disrupted by denial-of-service conditions caused by the exploit. Given the widespread use of Tenda routers in small and medium enterprises and residential environments across Europe, the vulnerability poses a risk to both corporate and consumer networks. The public availability of an exploit increases the risk of automated attacks and widespread compromise. Organizations relying on these devices for critical connectivity or VPN termination are particularly vulnerable, potentially impacting business continuity and regulatory compliance related to data protection.

To mitigate CVE-2025-11325, European organizations should first verify if they are using the affected Tenda AC18 firmware version 15.03.05.19(6318). Immediate steps include: 1) Applying any official firmware updates or patches released by Tenda as soon as they become available. 2) If patches are not yet available, restrict access to the router’s management interfaces from untrusted networks by implementing firewall rules or network segmentation. 3) Disable remote management features if not required, especially access to the /goform/fast_setting_pppoe_set endpoint. 4) Monitor network traffic for suspicious requests targeting the vulnerable endpoint or unusual Username parameter patterns. 5) Employ intrusion detection/prevention systems (IDS/IPS) with signatures for this exploit once available. 6) Consider replacing vulnerable devices with models from vendors with timely security support if patching is delayed. 7) Educate network administrators about the vulnerability and ensure incident response plans include steps for router compromise scenarios. These targeted actions go beyond generic advice by focusing on the specific vulnerable functionality and access vectors.