CVE-2025-29515 in DSL-7740C
Summary
by MITRE • 08/25/2025
Incorrect access control in the DELT_file.xgi endpoint of D-Link DSL-7740C with firmware DSL7740C.V6.TR069.20211230 allows attackers to modify arbitrary settings within the device's XML database, including the administrator’s password.
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Analysis
by VulDB Data Team • 09/03/2025
The vulnerability identified as CVE-2025-29515 represents a critical access control flaw within the DELT_file.xgi endpoint of D-Link DSL-7740C routers running firmware version DSL7740C.V6.TR069.20211230. This issue stems from improper authentication and authorization mechanisms that allow unauthenticated or improperly authenticated attackers to manipulate the device's XML database configuration files. The vulnerability specifically affects the TR-069 management protocol implementation within the router's web interface, which is commonly used for remote device management and configuration. The flaw enables attackers to gain unauthorized access to administrative functions that should be restricted to authorized personnel only. This misconfiguration creates a path for attackers to modify critical system parameters including administrative credentials, potentially leading to complete device compromise and persistent unauthorized access.
The technical implementation of this vulnerability demonstrates a classic case of insufficient access control validation within the router's web application layer. The DELT_file.xgi endpoint fails to properly verify user credentials or roles before allowing modification operations against the XML database structure. This weakness falls under CWE-285, which addresses improper authorization issues in software systems. Attackers can exploit this by directly accessing the vulnerable endpoint without requiring valid authentication credentials, or by leveraging session management flaws to escalate privileges. The XML database modification capability provides attackers with direct access to the router's configuration files, allowing them to alter network settings, firewall rules, and most critically, administrative passwords that control full device access. The vulnerability's exploitation requires minimal technical expertise and can be accomplished through standard web application attack vectors.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass complete network compromise and persistent backdoor access. Once an attacker successfully modifies the administrator password through the vulnerable endpoint, they gain full administrative privileges over the router, enabling them to modify routing tables, configure port forwarding rules, implement DNS redirection, and potentially establish persistent access points. This compromise can affect not only the individual device but also the broader network segment it serves, as routers often act as gateways and security boundaries. The vulnerability creates an ideal environment for attackers to establish persistent access, conduct man-in-the-middle attacks, or redirect network traffic to malicious destinations. From an attack lifecycle perspective, this vulnerability maps to multiple ATT&CK techniques including T1078 for valid accounts and T1566 for credential harvesting, while also enabling T1046 for network service scanning and T1059 for command execution.
Mitigation strategies for CVE-2025-29515 must address both immediate remediation and long-term security posture improvements. The most effective immediate solution involves firmware updates from D-Link that implement proper access control validation and authentication checks for the DELT_file.xgi endpoint. Network administrators should also implement network segmentation to limit access to administrative interfaces and employ network monitoring to detect unauthorized access attempts. Additional protective measures include disabling unnecessary services, implementing strong network access controls, and regularly reviewing access logs for suspicious activities. Security teams should also consider deploying intrusion detection systems that can identify exploitation attempts targeting known vulnerable endpoints. The vulnerability highlights the importance of proper input validation and access control implementation in web applications, aligning with security best practices outlined in NIST SP 800-53 and ISO 27001 standards. Regular vulnerability assessments and penetration testing should be conducted to identify similar access control flaws in other network devices and applications.