Critical Buffer Overflow Vulnerability in Tenda A15 Router

 

Critical Buffer Overflow Vulnerability in Tenda A15 Router

CVE-2025-4897 is a critical security vulnerability affecting the Tenda A15 router, specifically firmware versions 15.13.07.09 and 15.13.07.13. This vulnerability resides in the HTTP POST Request Handler component, within an unspecified part of the file /goform/multimodalAdd. The issue is a buffer overflow caused by improper handling of input data, which can be exploited remotely by an attacker.

Details of CVE-2025-4897

• Affected Product: Tenda A15 router
• Affected Versions: Firmware versions 15.13.07.09 and 15.13.07.13
• Vulnerable Component: HTTP POST Request Handler (/goform/multimodalAdd)
• Type of Vulnerability: Buffer overflow
• Attack Vector: Remote (via network)
• Severity: Critical, with a CVSS v3.1 score of 8.8 (High)
• Exploit Status: Publicly disclosed and exploitable
• Impact: Successful exploitation can lead to arbitrary code execution, potentially allowing attackers to take control of the device or disrupt its operation.

How the Vulnerability Works

Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, overwriting adjacent memory. In this case, the HTTP POST request handler does not properly validate or limit the size of input data sent to the /goform/multimodalAdd endpoint, allowing attackers to craft malicious POST requests that overflow the buffer. This can corrupt memory and enable execution of malicious code remotely. 

Potential Impact

• Remote Code Execution: Attackers can gain control over the router.
• Denial of Service: The device may crash or become unresponsive.
• Network Compromise: As the router is a critical network device, its compromise can lead to broader network security issues.

Mitigation and Recommendations

• Firmware Update: Users should update their Tenda A15 routers to the latest firmware version beyond 15.13.07.13 once available, as this is the most effective way to fix the vulnerability11.
• Network Security: Until patched, restrict access to the router’s management interface from untrusted networks.
• Monitor for Exploits: Given the exploit has been publicly disclosed, monitoring network traffic for suspicious POST requests targeting /goform/multimodalAdd is advisable.

Sample Scenario of Exploitation

1. An attacker scans for Tenda A15 routers exposed on the internet.
2. The attacker crafts a malicious HTTP POST request targeting /goform/multimodalAdd with specially crafted payload data designed to overflow the buffer.
3. The router processes the request, triggering the buffer overflow.
4. The attacker’s payload executes arbitrary code on the router, potentially opening a backdoor or disrupting service.
5. The attacker can now control the router remotely, intercept traffic, or launch further attacks on the internal network.

This vulnerability highlights the critical importance of secure input validation in network device firmware and the risks posed by exposed management interfaces. Immediate firmware updates and network access controls are essential to mitigate CVE-2025-4897