CVE-2025-29386 in AC9
Summary
by MITRE • 03/14/2025
In Tenda AC9 v1.0 V15.03.05.14_multi, the mac parameter of /goform/AdvSetMacMtuWan has a stack overflow vulnerability, which can lead to remote arbitrary code execution.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 06/04/2025
The vulnerability identified as CVE-2025-29386 affects the Tenda AC9 v1.0 V15.03.05.14_multi router firmware, representing a critical stack overflow flaw within the web interface's Advanced Settings module. This vulnerability specifically targets the mac parameter in the /goform/AdvSetMacMtuWan form handler, which processes user-supplied input without adequate validation or bounds checking. The flaw exists in the firmware's handling of network configuration parameters, where the device fails to properly sanitize input data before processing it in memory. The stack overflow occurs when an attacker submits a maliciously crafted mac parameter value that exceeds the allocated buffer space, causing the program to overwrite adjacent memory locations on the stack. This memory corruption can potentially overwrite critical program execution elements such as return addresses or function pointers, enabling attackers to redirect code execution flow. The vulnerability is particularly concerning because it allows for remote code execution without requiring authentication, making it accessible to attackers over the network. The issue stems from improper input validation practices and inadequate memory management within the router's web application framework, creating an attack surface that can be exploited from any location with network access to the device.
The technical exploitation of this vulnerability follows established patterns for stack-based buffer overflow attacks, where the attacker crafts a payload that overflows the designated buffer space and overwrites the stack frame. The CWE-121 classification applies here as the vulnerability involves stack-based buffer overflow conditions where insufficient space is allocated for data storage. The attack vector is classified as network-based remote execution, aligning with ATT&CK technique T1210 for exploiting vulnerabilities in network infrastructure devices. The vulnerability's impact extends beyond simple code execution to potentially allow full system compromise, as the router's web interface typically runs with elevated privileges. The flaw demonstrates poor defensive programming practices, specifically the absence of input length validation and secure memory handling mechanisms. The affected parameter processing occurs within the device's embedded web server component, which likely uses standard C-based programming without modern stack protection features such as stack canaries or address space layout randomization. This makes the exploitation more straightforward and reliable compared to systems with stronger security mitigations in place.
The operational impact of CVE-2025-29386 represents a severe risk to network security infrastructure, particularly in enterprise and residential environments where Tenda routers are deployed. Remote code execution capabilities enable attackers to gain complete control over the affected device, potentially allowing them to establish persistent backdoors, redirect network traffic, or use the compromised router as a pivot point for attacking other network segments. The vulnerability can be exploited by attackers who do not require physical access or prior authentication credentials, making it particularly dangerous for unsecured networks. Once exploited, the attacker could modify network configuration settings, disable security features, or install malicious firmware versions. The attack surface is further expanded due to the widespread deployment of this router model, potentially affecting thousands of devices globally. Organizations using these devices may experience significant security breaches, including data exfiltration, man-in-the-middle attacks, or the establishment of command and control channels. The vulnerability also poses risks to network availability, as attackers could potentially cause device crashes or reboots through malformed input. The lack of authentication requirements for exploitation means that this vulnerability could be actively exploited by automated scanning tools, leading to widespread compromise of affected networks.
Mitigation strategies for CVE-2025-29386 should prioritize immediate firmware updates from Tenda, as the vendor is likely to release patches addressing the buffer overflow condition. Network administrators should implement network segmentation and access controls to limit exposure of these devices to untrusted networks, particularly by placing routers in protected network zones. The implementation of network monitoring solutions can help detect anomalous traffic patterns that may indicate exploitation attempts, including unusual requests to the vulnerable form handler endpoint. Device administrators should consider disabling unnecessary web interface access and restricting access to only trusted IP addresses. Network administrators should also implement intrusion detection systems that can identify and alert on suspicious requests to the /goform/AdvSetMacMtuWan endpoint. The vulnerability highlights the importance of secure coding practices and input validation in embedded systems, suggesting that organizations should conduct regular security assessments of their network infrastructure devices. Organizations should also maintain detailed inventories of all network devices and their firmware versions to quickly identify and remediate vulnerable systems. The use of network access control lists and firewall rules can help prevent unauthorized access to the router's management interfaces, reducing the attack surface for this and similar vulnerabilities. Regular security audits of embedded systems and firmware updates should be prioritized to address similar vulnerabilities before they can be exploited by threat actors.