CVE-2025-69700 in FH1203
Summary
by MITRE • 02/23/2026
Tenda FH1203 V2.0.1.6 contains a stack-based buffer overflow vulnerability in the modify_add_client_prio function, which is reachable via the formSetClientPrio CGI handler.
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Analysis
by VulDB Data Team • 02/23/2026
The CVE-2025-69700 vulnerability represents a critical stack-based buffer overflow flaw discovered in the Tenda FH1203 router firmware version V2.0.1.6. This vulnerability resides within the modify_add_client_prio function, which is exposed through the formSetClientPrio Common Gateway Interface handler. The affected device operates as a wireless router and access point, making it a prime target for attackers seeking to compromise network infrastructure. The vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing within the stack memory space.
The technical exploitation of this vulnerability occurs when an attacker submits maliciously crafted input parameters to the formSetClientPrio CGI endpoint. The modify_add_client_prio function does not perform proper bounds checking on the input data, allowing an attacker to overflow the allocated stack buffer and overwrite adjacent memory locations. This type of buffer overflow falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue that enables arbitrary code execution. The vulnerability's reachability through the CGI interface means that remote exploitation is possible without requiring physical access to the device or authentication credentials.
The operational impact of this vulnerability extends beyond simple remote code execution, as it can enable attackers to gain full administrative control over the affected router. Once exploited, the attacker can modify network configurations, redirect traffic through malicious proxies, establish persistent backdoors, or use the device as a launching point for attacks against other networked systems. The Tenda FH1203 device serves as a network gateway, making it a strategic target for attackers seeking to establish persistent access within corporate or residential networks. The vulnerability also aligns with ATT&CK technique T1059.007 Command and Scripting Interpreter: JavaScript, as the CGI handler interface may process JavaScript-based input that could be manipulated to trigger the buffer overflow.
Mitigation strategies for CVE-2025-69700 should prioritize immediate firmware updates from Tenda, as the vendor has likely released patches addressing this specific vulnerability. Network administrators should implement network segmentation and firewall rules to limit access to the router's management interfaces, particularly restricting access to the formSetClientPrio endpoint. Additional defensive measures include deploying intrusion detection systems to monitor for suspicious CGI request patterns and implementing network access control measures to prevent unauthorized devices from connecting to the network. The vulnerability demonstrates the importance of proper input validation and memory management practices in embedded systems, particularly those handling network requests from untrusted sources. Organizations should also consider conducting vulnerability assessments of their entire network infrastructure to identify other potentially affected devices running similar firmware versions. The exploitability of this vulnerability highlights the critical need for embedded device security practices and the importance of regular firmware updates to address known security flaws.