CVE-2025-57571 Overview
CVE-2025-57571 is a buffer overflow vulnerability [CWE-120] affecting Tenda F3 routers running firmware version V12.01.01.48_multi and later. The flaw resides in the goform/setNAT endpoint, where the macFilterList parameter is processed without adequate boundary checking. An attacker who can reach the device management interface over the network can send a crafted request that overruns a fixed-size buffer. Successful exploitation impacts confidentiality, integrity, and availability on the affected device.
Critical Impact
Attackers with network access to the router's web interface can trigger memory corruption via the macFilterList parameter, potentially disrupting device operation or manipulating router behavior.
Affected Products
- Tenda F3 router (hardware)
- Tenda F3 firmware version 12.01.01.48
- Tenda F3 firmware versions released after V12.01.01.48_multi
Discovery Timeline
- 2025-09-10 - CVE-2025-57571 published to NVD
- 2026-07-05 - Last updated in NVD database
Technical Details for CVE-2025-57571
Vulnerability Analysis
The Tenda F3 router exposes a web management interface that handles NAT configuration through the goform/setNAT handler. This handler reads the macFilterList parameter from HTTP requests and copies its contents into a fixed-size stack or heap buffer. The copy operation does not validate the length of attacker-supplied data against the destination buffer size.
When an attacker submits an overly long value for macFilterList, the excess bytes overwrite adjacent memory. On embedded MIPS or ARM devices such as the Tenda F3, this typically results in corrupted stack frames, altered return addresses, or overwritten function pointers. The outcome ranges from device crash and reboot to potential control-flow hijacking depending on memory layout and mitigations available on the platform.
The attack complexity is elevated because reliable exploitation on embedded firmware requires knowledge of the specific memory layout and any protections present. However, denial of service through crash is straightforward once the vulnerable endpoint is reachable.
Root Cause
The root cause is missing input length validation on the macFilterList parameter inside the setNAT form handler. The firmware trusts client-supplied data and uses unchecked copy operations such as strcpy or sprintf against a fixed-length buffer, classifying the flaw under [CWE-120] (Classic Buffer Overflow).
Attack Vector
The vulnerability is exploitable over the network against any Tenda F3 device that exposes the web administration interface. An attacker sends an HTTP POST request to /goform/setNAT containing an oversized macFilterList value. Because authentication requirements on Tenda web endpoints are historically weak, the endpoint may be reachable without valid credentials on default configurations. The vulnerability is documented in the GitHub CVE-2025-57571 Documentation.
Detection Methods for CVE-2025-57571
Indicators of Compromise
- Unexpected reboots or crashes of the Tenda F3 router coinciding with inbound HTTP traffic to /goform/setNAT.
- HTTP requests to goform/setNAT containing abnormally long macFilterList parameter values, typically exceeding a few hundred bytes.
- Loss of NAT or firewall functionality following administrative interface access from untrusted networks.
Detection Strategies
- Inspect network traffic for POST requests targeting /goform/setNAT and flag payloads with excessive parameter length in macFilterList.
- Deploy IDS or IPS signatures that match oversized form values against Tenda web endpoints.
- Correlate router availability alerts with recent management-plane HTTP requests to identify probable exploitation attempts.
Monitoring Recommendations
- Log all HTTP requests to the router's management interface and forward them to a central log store for analysis.
- Monitor for repeated crash-and-reboot cycles on the affected device, which indicate probing or exploitation attempts.
- Track exposure of router administrative interfaces to WAN-side or untrusted LAN segments.
How to Mitigate CVE-2025-57571
Immediate Actions Required
- Restrict access to the Tenda F3 web management interface to trusted management VLANs only, and block WAN-side administration.
- Change default administrative credentials and enforce strong passwords to reduce unauthorized access to goform/setNAT.
- Replace end-of-life or unsupported Tenda F3 units with actively maintained hardware where a vendor patch is not available.
Patch Information
No vendor advisory or firmware fix has been published in the referenced sources at the time of writing. Consult the Tenda support portal for firmware updates addressing CVE-2025-57571 and monitor the GitHub CVE-2025-57571 Documentation for additional technical details.
Workarounds
- Disable remote (WAN) administration on the Tenda F3 router so /goform/setNAT is not reachable from the internet.
- Segment the router management interface behind a firewall that restricts source IP addresses to a small administrative allowlist.
- Where feasible, disable MAC filtering configuration features via NAT settings until a patched firmware release is available.
# Configuration example: block external access to router admin interface
# Example iptables rule on an upstream gateway
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_ip> -p tcp --dport 443 -j DROP
# Allow only trusted management subnet
iptables -I FORWARD -s 10.10.0.0/24 -d <router_ip> -p tcp --dport 80 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
