CVE-2025-12596: Tenda AC23 Buffer Overflow Vulnerability

CVE-2025-12596 Overview

A buffer overflow vulnerability has been identified in Tenda AC23 wireless router firmware version 16.03.07.52. The vulnerability exists in the saveParentControlInfo function within the /goform/saveParentControlInfo endpoint. By manipulating the Time argument, an attacker can trigger a buffer overflow condition. This vulnerability can be exploited remotely and the exploit has been publicly disclosed.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability to potentially execute arbitrary code on vulnerable Tenda AC23 routers, compromising network security and enabling further attacks on connected devices.

Affected Products

• Tenda AC23 Firmware version 16.03.07.52
• Tenda AC23 Hardware version 1.0

Discovery Timeline

• 2025-11-02 - CVE-2025-12596 published to NVD
• 2025-11-05 - Last updated in NVD database

Technical Details for CVE-2025-12596

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-120 (Buffer Copy without Checking Size of Input). The saveParentControlInfo function fails to properly validate the length of the Time parameter before copying it into a fixed-size buffer. When an attacker supplies an excessively long value for this parameter, the function writes beyond the allocated buffer boundaries, corrupting adjacent memory regions.

The vulnerability is accessible via the network without requiring physical access to the device. While authentication is required to access the vulnerable endpoint, authenticated users can exploit this flaw to gain elevated privileges or execute arbitrary code on the device.

Root Cause

The root cause of this vulnerability stems from insufficient input validation in the saveParentControlInfo function. The firmware does not verify that the Time argument conforms to expected length constraints before processing. The function uses an unsafe memory copy operation that lacks bounds checking, allowing data to overflow the destination buffer when provided with maliciously crafted input.

Attack Vector

The attack can be executed remotely over the network by sending a specially crafted HTTP POST request to the /goform/saveParentControlInfo endpoint. An attacker must be authenticated to access this endpoint, typically through valid router credentials. Once authenticated, the attacker sends an oversized value in the Time parameter, triggering the buffer overflow.

This could allow an attacker to overwrite critical memory structures, potentially leading to denial of service, arbitrary code execution, or complete device compromise. Given that routers often serve as network gateways, a successful exploit could provide an attacker with a foothold for lateral movement within the target network.

For technical details and proof-of-concept information, refer to the GitHub CVE Issue Discussion.

Detection Methods for CVE-2025-12596

Indicators of Compromise

• Unusual HTTP POST requests to /goform/saveParentControlInfo with abnormally long Time parameter values
• Unexpected router reboots or crashes that may indicate exploitation attempts
• Suspicious network traffic originating from the router to external destinations
• Modified router configurations or unexpected administrative access

Detection Strategies

• Monitor HTTP traffic to router management interfaces for requests containing oversized parameters
• Implement network-based intrusion detection rules to identify buffer overflow exploitation patterns targeting Tenda devices
• Deploy web application firewalls (WAF) to filter malicious requests to router endpoints
• Review router access logs for authentication attempts followed by anomalous POST requests

Monitoring Recommendations

• Enable logging on the Tenda AC23 router if available and forward logs to a centralized SIEM solution
• Monitor for unexpected outbound connections from router IP addresses
• Implement network segmentation to isolate IoT and network infrastructure devices
• Conduct regular firmware version audits to identify devices running vulnerable versions

How to Mitigate CVE-2025-12596

Immediate Actions Required

• Check if your Tenda AC23 router is running firmware version 16.03.07.52 and plan for immediate mitigation
• Restrict management interface access to trusted internal networks only
• Disable remote management features if not required for operations
• Implement strong, unique credentials for router administration
• Monitor for vendor firmware updates from Tenda

Patch Information

At the time of publication, no official patch has been released by Tenda for this vulnerability. Users should monitor the Tenda Official Website for security updates and firmware releases. Additional vulnerability details are available through VulDB ID #330891.

Workarounds

• Disable WAN-side access to the router management interface to prevent remote exploitation
• Place the router behind a firewall that can filter and inspect HTTP traffic to management endpoints
• Implement access control lists (ACLs) to restrict which IP addresses can access the router's web interface
• Consider replacing vulnerable devices with alternative hardware if no patch becomes available

# Example: Restrict management access to specific IP ranges (if supported by firmware)
# Access router configuration interface and navigate to:
# Administration > Remote Management > Disable
# Administration > Access Control > Allow only trusted IP ranges