CVE-2025-29515 is a security vulnerability identified in the D-Link DSL-7740C router, specifically affecting the firmware version DSL7740C.V6.TR069.20211230. The vulnerability arises from incorrect access control implemented in the DELT_file.xgi endpoint. This endpoint is responsible for handling XML database modifications within the device. Due to improper access restrictions, an attacker can exploit this endpoint to modify arbitrary settings stored in the device's XML database. Critically, this includes the ability to change the administrator's password, effectively granting the attacker full administrative control over the device. The vulnerability does not require authentication or user interaction, making it particularly dangerous. Although no known exploits have been reported in the wild yet, the potential for exploitation is significant given the nature of the flaw. The lack of a CVSS score indicates that the vulnerability is newly published and may not yet have been fully assessed. However, the ability to alter administrative credentials and device configuration remotely represents a severe security risk. The vulnerability affects a specific firmware version of the DSL-7740C model, which is a DSL router commonly deployed in broadband networks. Attackers exploiting this flaw could gain persistent control over the device, intercept or redirect network traffic, and potentially use the compromised router as a foothold for further attacks within the network environment.

For European organizations, the impact of this vulnerability can be substantial. Many enterprises and ISPs in Europe utilize D-Link DSL routers, including the DSL-7740C model, for broadband connectivity. A successful exploitation could lead to unauthorized administrative access, allowing attackers to manipulate network configurations, intercept sensitive communications, or launch man-in-the-middle attacks. This could compromise the confidentiality and integrity of organizational data and disrupt availability by causing network outages or degraded performance. Furthermore, compromised routers could be leveraged to pivot into internal networks, facilitating lateral movement and increasing the risk of broader network breaches. Given the critical role of such devices in network infrastructure, exploitation could impact business continuity, regulatory compliance (e.g., GDPR), and customer trust. The absence of known exploits currently provides a window for proactive mitigation, but the risk remains high due to the ease of exploitation and the critical nature of the affected settings.

Organizations should immediately verify if they are using the D-Link DSL-7740C router with the affected firmware version DSL7740C.V6.TR069.20211230. If so, they should seek firmware updates or patches from D-Link, even though none are currently listed, and apply them as soon as they become available. In the interim, restricting access to the router's management interfaces to trusted internal networks only is essential. Network segmentation should be employed to isolate management interfaces from general user access. Additionally, monitoring network traffic for unusual activity related to the DELT_file.xgi endpoint can help detect exploitation attempts. Implementing strong network perimeter defenses, such as firewalls and intrusion detection/prevention systems configured to detect anomalous XML requests, is recommended. Organizations should also consider replacing vulnerable devices if no patch is forthcoming and conduct regular audits of router configurations and credentials. Finally, raising user awareness about the risks of unauthorized device access and enforcing strict password policies will help mitigate potential impacts.