CVE-2025-69766 in AX3
Summary
by MITRE • 01/21/2026
Tenda AX3 firmware v16.03.12.11 contains a stack-based buffer overflow in the formGetIptv function due to improper handling of the citytag stack buffer, which may result in memory corruption and remote code execution.
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Analysis
by VulDB Data Team • 01/22/2026
The vulnerability identified as CVE-2025-69766 represents a critical stack-based buffer overflow flaw within the Tenda AX3 wireless router firmware version 16.03.12.11. This issue manifests in the formGetIptv function where inadequate input validation and memory management practices create a condition that allows attackers to overwrite adjacent stack memory locations. The vulnerability specifically targets the citytag stack buffer, which serves as an insufficiently protected memory region that cannot accommodate potentially malicious input data. The improper handling of this buffer creates a pathway for attackers to manipulate the program's execution flow through carefully crafted input sequences that exceed the allocated memory boundaries. Such buffer overflow conditions are particularly dangerous in network-facing applications where unauthenticated remote exploitation is possible.
The technical exploitation of this vulnerability enables adversaries to achieve arbitrary code execution on the affected device, potentially leading to complete system compromise. When the formGetIptv function processes user-supplied input through the citytag parameter, the lack of proper bounds checking allows attackers to overflow the designated stack buffer and overwrite return addresses, function pointers, or other critical memory locations. This memory corruption can be leveraged to redirect program execution to attacker-controlled code segments, effectively granting remote attackers full administrative privileges over the router. The vulnerability's classification aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions. The attack surface is further expanded by the fact that this function likely operates within a web interface or network service that accepts external input without sufficient sanitization.
The operational impact of CVE-2025-69766 extends beyond simple remote code execution to encompass complete network infrastructure compromise. Compromised routers can serve as persistent entry points for attackers to establish backdoors, redirect network traffic, or launch further attacks against internal network segments. The vulnerability's presence in a consumer-grade wireless router means that affected devices may be exposed to the internet without proper network segmentation, amplifying the potential for widespread exploitation. Network administrators face the challenge of identifying potentially compromised devices within their networks, as the attack may not be immediately detectable through standard monitoring tools. This vulnerability directly maps to ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1071.004 for Application Layer Protocol, as attackers can leverage the compromised device to execute commands and establish covert communication channels.
Mitigation strategies for this vulnerability require immediate firmware updates from Tenda, as the manufacturer must address the root cause through proper input validation and buffer management practices. Network administrators should implement network segmentation to limit the exposure of affected devices to external networks, while also deploying intrusion detection systems to monitor for suspicious traffic patterns that may indicate exploitation attempts. The implementation of input sanitization measures, including length validation and parameterized input handling, can provide additional defense-in-depth layers against similar vulnerabilities. Security assessments should include thorough vulnerability scanning of all network devices to identify potentially affected Tenda AX3 routers, with particular attention to those operating in exposed network zones. Organizations should also consider implementing network access controls to restrict access to device management interfaces and establish monitoring protocols to detect anomalous behavior indicative of compromise. Regular firmware update policies and network security awareness training for personnel managing these devices will help reduce the risk of exploitation and maintain overall network security posture.