CVE-2025-6887 in AC5
Summary
by MITRE • 06/30/2025
A vulnerability was found in Tenda AC5 15.03.06.47 and classified as critical. Affected by this issue is some unknown functionality of the file /goform/SetSysTimeCfg. The manipulation of the argument time/timeZone leads to stack-based buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 06/30/2025
The vulnerability identified as CVE-2025-6887 represents a critical stack-based buffer overflow flaw within the Tenda AC5 router firmware version 15.03.06.47. This issue resides in the /goform/SetSysTimeCfg endpoint which handles system time configuration functionality. The vulnerability specifically manifests when processing the time and timeZone parameters, creating a condition where insufficient input validation allows malicious actors to overwrite adjacent memory locations on the stack. The attack vector is remote, meaning an unauthenticated attacker can exploit this vulnerability from outside the network without requiring physical access or prior authentication. This classification as a critical vulnerability stems from the potential for arbitrary code execution and complete system compromise when exploited successfully. The disclosure of exploitation techniques further amplifies the risk as attackers can readily leverage this vulnerability without requiring advanced technical knowledge or specialized tools.
The technical implementation of this vulnerability follows a classic stack buffer overflow pattern where the time and timeZone arguments are processed without adequate bounds checking. When these parameters exceed the allocated buffer space, they overwrite adjacent stack memory locations including return addresses and control data. This overflow enables attackers to manipulate the program flow and potentially execute malicious code with the privileges of the affected service. The CWE-121 classification applies here as the vulnerability involves stack-based buffer overflow conditions where insufficient boundary checking allows buffer overflow scenarios. The attack surface is particularly concerning given that the affected endpoint is part of the web-based management interface, making it accessible through standard HTTP protocols and potentially exploitable via web browsers or automated scanning tools.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise and potential network infiltration. Successful exploitation could allow attackers to gain root access to the router, enabling them to modify network configurations, install persistent backdoors, or use the device as a pivot point for attacking internal network resources. The router's role as a network gateway makes it a prime target for attackers seeking to establish persistent access within corporate or residential networks. This vulnerability could also facilitate broader attacks including man-in-the-middle operations, DNS poisoning, or serving as a command and control node for botnet activities. The public disclosure of exploitation methods means that automated scanning tools could readily identify vulnerable devices and initiate attacks without human intervention, creating a significant risk for widespread exploitation across affected deployments.
Mitigation strategies for CVE-2025-6887 require immediate firmware updates from Tenda to address the buffer overflow condition in the SetSysTimeCfg endpoint. Network administrators should disable unnecessary remote management features and implement strict firewall rules to restrict access to the router's web management interface. The principle of least privilege should be applied by limiting access to administrative functions to trusted IP addresses only. Network segmentation can help contain potential exploitation by isolating affected devices from critical network segments. Regular vulnerability scanning and network monitoring should be implemented to detect potential exploitation attempts. The ATT&CK framework's T1071.001 technique applies here as attackers could leverage the compromised router for command and control communications. Organizations should also implement network intrusion detection systems to monitor for unusual traffic patterns that might indicate exploitation attempts. Additionally, the use of secure network protocols and regular security audits can help identify and remediate similar vulnerabilities in other network infrastructure components.