CVE-2025-7531 is a critical stack-based buffer overflow vulnerability identified in the Tenda FH1202 router, specifically version 1.2.0.14(408). The flaw exists in the function fromPptpUserSetting within the /goform/PPTPUserSetting endpoint. An attacker can exploit this vulnerability by manipulating the 'delno' argument, which leads to a stack-based buffer overflow condition. This type of vulnerability allows an attacker to overwrite the stack memory, potentially enabling arbitrary code execution, denial of service, or system compromise. The vulnerability is remotely exploitable without requiring user interaction or authentication, increasing its risk profile. The CVSS 4.0 base score is 8.7 (high severity), reflecting the vulnerability's ease of exploitation (network vector, low attack complexity, no privileges or user interaction needed) and its significant impact on confidentiality, integrity, and availability. Although no public exploits are currently reported in the wild, the disclosure of the exploit code increases the likelihood of active exploitation attempts. The vulnerability affects a specific firmware version of the Tenda FH1202 router, a device commonly used in small office and home office environments for internet connectivity, often deployed in various regions including Europe. The absence of an official patch or mitigation from the vendor at the time of disclosure further elevates the risk to users of this device version.

For European organizations, this vulnerability poses a significant threat, especially to small and medium enterprises (SMEs) and home office setups relying on Tenda FH1202 routers. Successful exploitation could lead to full compromise of the affected router, allowing attackers to intercept, modify, or redirect network traffic, potentially leading to data breaches, espionage, or lateral movement within corporate networks. The compromise of network infrastructure devices like routers undermines the confidentiality, integrity, and availability of organizational communications. Given the remote and unauthenticated nature of the exploit, attackers can target vulnerable devices en masse, leading to widespread disruption or use of compromised routers as footholds for further attacks. This risk is exacerbated in sectors with sensitive data or critical infrastructure, such as finance, healthcare, and government agencies. Additionally, the public availability of exploit code increases the likelihood of automated scanning and exploitation campaigns targeting vulnerable devices across Europe.

Immediate mitigation steps include isolating affected Tenda FH1202 devices from critical network segments and the internet to prevent exploitation. Network administrators should monitor network traffic for unusual activity, especially targeting the /goform/PPTPUserSetting endpoint. Deploying network-level protections such as intrusion detection/prevention systems (IDS/IPS) with signatures tuned to detect exploitation attempts against this vulnerability is recommended. Where possible, disable PPTP VPN functionality on the router if not in use, as this reduces the attack surface. Organizations should engage with Tenda support channels to obtain firmware updates or patches addressing this vulnerability; if unavailable, consider replacing affected devices with models from vendors with timely security support. Additionally, implementing network segmentation and strict access controls can limit the impact of a compromised router. Regular vulnerability scanning and asset inventory updates will help identify and track affected devices. Finally, educating users about the risks and encouraging prompt reporting of network anomalies will aid in early detection and response.