CVE-2025-7913 in TOTOLINK
Summary
by MITRE • 07/21/2025
A vulnerability, which was classified as critical, was found in TOTOLINK T6 4.1.5cu.748_B20211015. Affected is the function updateWifiInfo of the component MQTT Service. The manipulation of the argument serverIp leads to buffer overflow. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 07/24/2025
The vulnerability identified as CVE-2025-7913 represents a critical buffer overflow flaw within the TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015. This issue specifically affects the MQTT Service component, which is responsible for managing wireless network information updates through the updateWifiInfo function. The vulnerability arises from insufficient input validation when processing the serverIp argument, creating a condition where maliciously crafted input can exceed the allocated buffer space and overwrite adjacent memory regions. The affected device operates under the TOTOLINK T6 model, which is commonly deployed in residential and small office environments, making it a potentially widespread target for exploitation.
The technical nature of this vulnerability places it firmly within the scope of CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The remote exploitability of this flaw means that attackers do not require physical access to the device to carry out malicious operations. The buffer overflow occurs during the processing of the serverIp parameter within the MQTT Service's updateWifiInfo function, where the device fails to properly validate or sanitize user-supplied input before copying it into a fixed-size buffer. This type of vulnerability can potentially lead to arbitrary code execution, system crashes, or complete device compromise, as the overflow allows attackers to overwrite critical program execution pointers and control flow registers.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it provides attackers with the capability to execute malicious code on the affected router. This could enable attackers to gain persistent access to the network, redirect traffic through malicious servers, or establish backdoors for future exploitation. The fact that the exploit has been publicly disclosed increases the risk profile significantly, as it removes the element of exploit scarcity that typically protects against zero-day attacks. Network administrators face the challenge of securing devices that may be actively targeted by threat actors who can leverage this vulnerability to compromise the entire network infrastructure, particularly in environments where the router serves as a gateway for multiple connected devices.
Mitigation strategies for CVE-2025-7913 should prioritize immediate firmware updates from TOTOLINK, as the vendor is expected to release patches addressing the buffer overflow in the MQTT Service component. Network segmentation and firewall rules can provide temporary protection by blocking unauthorized access to the router's management interfaces and MQTT service ports. Implementing intrusion detection systems that monitor for unusual traffic patterns or malformed MQTT packets can help detect exploitation attempts. Additionally, network administrators should consider disabling unnecessary services such as MQTT if they are not required for operations, reducing the attack surface. The vulnerability's classification as critical aligns with ATT&CK technique T1071.004, which covers application layer protocol usage, and T1059.007, which addresses command and scripting interpreters, as successful exploitation could enable attackers to execute commands on the compromised device and potentially escalate privileges to gain full administrative control over the network infrastructure.