CVE-2025-7853 Overview
CVE-2025-7853 is a stack-based buffer overflow vulnerability in the Tenda FH451 router running firmware version 1.0.0.9. The flaw resides in the fromSetIpBind function within the /goform/SetIpBind endpoint. An attacker can manipulate the page argument to overflow a fixed-size stack buffer. The vulnerability is remotely exploitable over the network and requires low privileges. Public exploit details have been disclosed, increasing the risk of opportunistic attacks against exposed devices. The weakness is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Critical Impact
Remote attackers can corrupt stack memory on the device, potentially leading to arbitrary code execution or denial of service against the router.
Affected Products
- Tenda FH451 router (hardware)
- Tenda FH451 firmware version 1.0.0.9
- Web management interface endpoint /goform/SetIpBind
Discovery Timeline
- 2025-07-19 - CVE-2025-7853 published to NVD
- 2025-07-23 - Last updated in NVD database
Technical Details for CVE-2025-7853
Vulnerability Analysis
The vulnerability exists in the fromSetIpBind handler responsible for processing IP binding configuration requests on the Tenda FH451 router. The handler reads the page parameter from an HTTP request to /goform/SetIpBind and copies it into a fixed-size stack buffer without validating the input length. Supplying an oversized page value overruns the destination buffer and overwrites adjacent stack data, including saved return addresses. Successful exploitation can divert control flow on the embedded MIPS or ARM processor used by the device. The publicly available proof-of-concept demonstrates how to trigger the overflow against the device's HTTP management interface.
Root Cause
The root cause is the absence of bounds checking when handling user-supplied input in the fromSetIpBind function. The firmware uses an unsafe string copy operation, treating attacker-controlled HTTP parameters as trusted input. This pattern, tracked as CWE-119, is recurrent in Tenda's /goform/* handlers across multiple product lines.
Attack Vector
An authenticated attacker on the same network or with reachability to the router's web management interface sends a crafted POST request to /goform/SetIpBind containing an oversized page parameter. If management is exposed to the WAN, the attack can be carried out remotely from the internet. No user interaction is required beyond delivering the HTTP request.
No verified exploitation code is reproduced here. Technical details and a proof-of-concept are documented in the public GitHub vulnerability writeup for fromSetIpBind.
Detection Methods for CVE-2025-7853
Indicators of Compromise
- HTTP POST requests to /goform/SetIpBind containing unusually long page parameter values.
- Repeated router reboots, crashes of the httpd process, or watchdog resets following management interface access.
- Unexpected configuration changes to IP-MAC binding entries on the FH451.
Detection Strategies
- Inspect HTTP traffic to the router management interface for parameter lengths that exceed expected bounds on page, particularly for the /goform/SetIpBind endpoint.
- Deploy network IDS/IPS signatures that flag oversized form parameters targeting Tenda /goform/* handlers.
- Correlate router crash events with preceding HTTP requests to identify exploitation attempts.
Monitoring Recommendations
- Enable syslog forwarding from the router to a centralized logging system and alert on httpd restarts.
- Monitor for unauthorized access to the router's administrative interface from unexpected source IPs or geographies.
- Track EPSS movement for CVE-2025-7853 (currently 0.885%, 75th percentile) as an indicator of exploitation likelihood trends.
How to Mitigate CVE-2025-7853
Immediate Actions Required
- Disable remote (WAN-side) management of the Tenda FH451 web interface.
- Restrict access to the LAN management interface to a small set of trusted administrative hosts.
- Rotate the router administrator password and review IP-MAC binding entries for unauthorized changes.
- Place the device behind a network segment that blocks untrusted clients from reaching /goform/SetIpBind.
Patch Information
At the time of publication, no vendor patch is referenced in the NVD record for CVE-2025-7853. Check the Tenda official website for firmware updates beyond version 1.0.0.9. Additional tracking details are available via VulDB entry 316943.
Workarounds
- Block inbound HTTP/HTTPS access to the router's management port from untrusted networks using an upstream firewall.
- Apply ACLs that limit /goform/SetIpBind access to administrative VLANs only.
- If the device is end-of-support or no fix is available, replace it with a supported router platform.
# Example upstream firewall rule to block external access to the FH451 management interface
# Replace ROUTER_IP and ADMIN_SUBNET with environment-specific values
iptables -A FORWARD -p tcp -d ROUTER_IP --dport 80 -s ADMIN_SUBNET -j ACCEPT
iptables -A FORWARD -p tcp -d ROUTER_IP --dport 80 -j DROP
iptables -A FORWARD -p tcp -d ROUTER_IP --dport 443 -s ADMIN_SUBNET -j ACCEPT
iptables -A FORWARD -p tcp -d ROUTER_IP --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
