CVE-2025-29520 in DSL-7740C
Summary
by MITRE • 08/26/2025
Incorrect access control in the Maintenance module of D-Link DSL-7740C with firmware DSL7740C.V6.TR069.20211230 allows authenticated attackers with low-level privileges to arbitrarily change the high-privileged account passwords and escalate privileges.
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Analysis
by VulDB Data Team • 09/03/2025
The vulnerability identified as CVE-2025-29520 represents a critical access control flaw within the Maintenance module of D-Link DSL-7740C routers running firmware version DSL7740C.V6.TR069.20211230. This issue stems from insufficient privilege validation mechanisms that permit authenticated users with minimal administrative rights to manipulate high-privileged accounts through password modification functions. The flaw exists in the router's web-based management interface where proper access control checks fail to validate whether the requesting user possesses adequate privileges to perform administrative operations on other user accounts.
The technical implementation of this vulnerability manifests through improper input validation and authorization checks within the Maintenance module's password change functionality. Attackers can exploit this weakness by crafting specific requests that bypass normal privilege escalation procedures, effectively allowing them to modify passwords for accounts with elevated permissions. This flaw directly violates the principle of least privilege and demonstrates inadequate separation of duties within the router's authentication framework. The vulnerability operates at the application layer and requires only basic authentication credentials to initiate the exploitation process, making it particularly dangerous as it can be leveraged by users who should not possess administrative capabilities.
From an operational impact perspective, this vulnerability creates a severe risk for network security infrastructure as it enables privilege escalation without requiring additional credentials or complex attack vectors. An authenticated attacker can leverage this weakness to gain full administrative control over the router's configuration, including access to network settings, user management, firewall rules, and potentially sensitive network traffic. The implications extend beyond simple password modification, as the compromised router could serve as a pivot point for broader network attacks, DNS tunneling, or redirection of network traffic. This vulnerability particularly affects enterprise and home network environments where D-Link DSL-7740C devices are deployed, potentially exposing entire networks to unauthorized access and manipulation.
Organizations should implement immediate mitigations including firmware updates from D-Link to address the access control flaw, network segmentation to isolate affected devices, and monitoring for unauthorized password change activities. The vulnerability aligns with CWE-284 which addresses improper access control issues, and represents a specific implementation of the broader ATT&CK technique T1078 for Valid Accounts and T1543 for Create or Modify System Process. Network administrators should also consider disabling unnecessary administrative functions, implementing strong password policies, and conducting regular security audits of network infrastructure devices. The flaw underscores the importance of proper privilege management and access control implementation in network devices, particularly those handling sensitive network configuration data.