CVE-2025-6940 in A702R
Summary
by MITRE • 07/01/2025
A vulnerability classified as critical was found in TOTOLINK A702R 4.0.0-B20230721.1521. Affected by this vulnerability is an unknown functionality of the file /boafrm/formParentControl of the component HTTP POST Request Handler. The manipulation of the argument submit-url leads to buffer overflow. The attack can be launched remotely. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 07/01/2025
The vulnerability identified as CVE-2025-6940 represents a critical buffer overflow flaw within the TOTOLINK A702R router firmware version 4.0.0-B20230721.1521. This issue resides in the HTTP POST Request Handler component, specifically within the /boafrm/formParentControl file which processes incoming web requests. The vulnerability manifests when an attacker manipulates the submit-url argument parameter, causing a buffer overflow condition that can potentially lead to arbitrary code execution or system compromise. The affected device operates a web-based management interface that handles various configuration parameters through HTTP POST requests, making it susceptible to remote exploitation without requiring physical access or authentication credentials.
The technical implementation of this vulnerability follows CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The buffer overflow occurs during the processing of the submit-url parameter within the HTTP POST handler, where input validation fails to properly constrain the length of user-supplied data. This flaw enables attackers to craft malicious requests that exceed the allocated buffer space, potentially overwriting critical program variables, return addresses, or other memory structures essential for proper program execution. The vulnerability's remote exploitability means that attackers can trigger the buffer overflow through network-based attacks without requiring local access to the device.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can potentially enable full system compromise and unauthorized access to network infrastructure. An attacker who successfully exploits this vulnerability could gain root-level privileges on the affected router, allowing them to modify network configurations, redirect traffic, install malicious software, or establish persistent backdoors within the network. The attack vector through the HTTP POST handler makes this particularly dangerous as it can be exploited through web-based interfaces, automated scanning tools, or social engineering techniques that trick users into submitting malicious requests to the router's management interface. Given that this vulnerability has been publicly disclosed, the risk of exploitation increases significantly as threat actors have access to specific techniques and tools required to leverage the flaw.
Mitigation strategies for CVE-2025-6940 should prioritize immediate firmware updates from TOTOLINK to address the buffer overflow vulnerability in the HTTP POST handler component. Network administrators should implement network segmentation and access controls to limit exposure of affected devices to untrusted networks, while also monitoring for suspicious network traffic patterns that may indicate exploitation attempts. The implementation of web application firewalls and intrusion detection systems can help detect and block malicious POST requests targeting the vulnerable submit-url parameter. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all instances of the affected firmware versions and ensure proper network monitoring for signs of compromise. The ATT&CK framework categorizes this vulnerability under T1210 - Exploitation of Remote Services, emphasizing the need for robust network security controls and regular firmware maintenance to prevent exploitation of such remote code execution vulnerabilities.