CVE-2025-7881 is a medium-severity vulnerability identified in the Mercusys MW301R router, specifically version 1.0.2 Build 190726 Rel.59423n. The vulnerability resides in the device's web interface component, where improper handling of the 'code' argument during the password recovery process leads to weak password recovery mechanisms. This flaw allows an attacker to remotely initiate the password recovery process without requiring user interaction or authentication, exploiting the weak validation or manipulation of the recovery code parameter. Although the exact internal code details are unspecified, the vulnerability enables an attacker to potentially reset or recover the router's administrative password, thereby gaining unauthorized access to the device's management interface. The vendor Mercusys was notified early but did not respond or provide a patch, and while no known exploits are currently observed in the wild, the exploit details have been publicly disclosed, increasing the risk of exploitation. The CVSS v4.0 base score is 5.1, reflecting a medium severity with network attack vector, low impact on integrity, and no impact on confidentiality or availability. The vulnerability does not require privileges or user interaction, making it easier to exploit remotely. Given the critical role of routers as network gateways, unauthorized access could lead to further network compromise or interception of traffic.

For European organizations, this vulnerability poses a significant risk primarily to small and medium enterprises or home offices using the Mercusys MW301R router, which is a low-cost consumer-grade device. Successful exploitation could allow attackers to gain administrative control over the router, enabling them to alter network configurations, redirect traffic, or deploy man-in-the-middle attacks. This could compromise the confidentiality and integrity of sensitive organizational data transmitted over the network. Additionally, attackers could use the compromised router as a foothold to pivot into internal networks or launch further attacks. The lack of vendor response and patch availability increases the window of exposure. Organizations relying on these devices without proper network segmentation or monitoring may face increased risk of data breaches or service disruptions. Given the medium CVSS score, the threat is moderate but should not be underestimated, especially in environments where these routers are deployed without additional security controls.

1. Immediate mitigation involves isolating Mercusys MW301R routers from critical network segments and restricting remote management access to trusted IP addresses only. 2. Disable remote password recovery features if possible or restrict access to the web interface via firewall rules. 3. Monitor network traffic for unusual access patterns or unauthorized configuration changes on these routers. 4. Replace affected devices with routers from vendors with active security support and patch management. 5. If replacement is not immediately feasible, implement strong network segmentation to limit the impact of a compromised router. 6. Regularly audit router configurations and change default credentials proactively. 7. Employ network intrusion detection systems (NIDS) to detect exploitation attempts targeting the password recovery process. 8. Stay informed on vendor updates or community patches and apply them promptly once available.