CVE-2026-3398 Overview
CVE-2026-3398 is a buffer overflow vulnerability in the Tenda F453 router running firmware version 1.0.0.3. The flaw resides in the fromAdvSetWan function within the /goform/AdvSetWan endpoint of the device's httpd web service. Attackers can exploit the issue by manipulating the wanmode or PPPOEPassword arguments to overflow internal buffers. The vulnerability is reachable over the network and requires only low-privilege authentication. Public disclosure of exploitation details has occurred, increasing the likelihood of opportunistic abuse against exposed devices.
Critical Impact
A remote authenticated attacker can trigger memory corruption in the httpd process, leading to potential code execution or denial of service on affected Tenda F453 routers.
Affected Products
- Tenda F453 router (hardware)
- Tenda F453 Firmware version 1.0.0.3
- Tenda httpd web management component
Discovery Timeline
- 2026-03-01 - CVE-2026-3398 published to NVD
- 2026-03-03 - Last updated in NVD database
Technical Details for CVE-2026-3398
Vulnerability Analysis
The vulnerability is classified under [CWE-119] — improper restriction of operations within the bounds of a memory buffer. It affects the fromAdvSetWan handler exposed by the embedded httpd web server on the Tenda F453. When a user submits advanced WAN configuration data through the /goform/AdvSetWan endpoint, the handler copies attacker-controlled input from the wanmode and PPPOEPassword POST parameters into fixed-size stack or heap buffers without enforcing length checks.
Because the affected function processes raw HTTP request data, an attacker who can reach the management interface can submit oversized parameter values to corrupt adjacent memory. Successful exploitation can crash the httpd daemon, disrupt router availability, or, depending on memory layout and stack canary protections on the MIPS or ARM target, lead to arbitrary code execution within the device firmware context.
Root Cause
The root cause is missing or insufficient bounds validation on the wanmode and PPPOEPassword parameters before they are copied into local buffers within fromAdvSetWan. Embedded vendor code paths frequently rely on unsafe routines such as strcpy or sprintf against fixed buffers, and the F453 firmware exhibits this pattern.
Attack Vector
Exploitation requires network access to the router's HTTP management interface and valid low-privilege credentials. An attacker sends a crafted POST request to /goform/AdvSetWan with an overlong wanmode or PPPOEPassword value. No user interaction is required. Devices with management exposed to the WAN or untrusted LAN segments are at highest risk. A publicly disclosed proof-of-concept is referenced in the GitHub Vulnerability Report and the VulDB Entry #348293.
No verified exploit code is reproduced here. Refer to the linked advisories for technical reproduction details.
Detection Methods for CVE-2026-3398
Indicators of Compromise
- Unexpected restarts or crashes of the httpd service on Tenda F453 devices
- HTTP POST requests to /goform/AdvSetWan containing abnormally long wanmode or PPPOEPassword values
- Unscheduled configuration changes to WAN settings outside of administrator activity
- Outbound connections from the router to unknown hosts following suspicious management traffic
Detection Strategies
- Inspect network logs for POST requests to /goform/AdvSetWan that exceed expected parameter lengths.
- Alert on repeated failed or malformed authentication attempts against the router web interface preceding configuration requests.
- Baseline normal administrative traffic patterns and flag deviations targeting WAN configuration endpoints.
Monitoring Recommendations
- Forward router syslog and web access logs to a centralized analytics platform for parameter-length anomaly detection.
- Monitor for unauthorized access to the router management VLAN or interface.
- Track firmware version inventory to identify Tenda F453 devices running the affected 1.0.0.3 build.
How to Mitigate CVE-2026-3398
Immediate Actions Required
- Restrict access to the router management interface to trusted administrative networks only.
- Disable WAN-side administration on all Tenda F453 devices until a vendor patch is available.
- Rotate credentials used for router administration to limit the value of any captured low-privilege accounts.
- Inventory affected devices running firmware 1.0.0.3 and prioritize them for replacement or isolation.
Patch Information
At the time of publication, no vendor advisory or fixed firmware release has been published. Monitor the Tenda Official Site and the VulDB CTI ID #348293 entry for updates. If a patch is not forthcoming, organizations should plan device replacement with a supported model.
Workarounds
- Place the Tenda F453 behind a network firewall that blocks inbound HTTP/HTTPS to the device from untrusted networks.
- Enforce strong, unique administrator credentials to reduce the risk of low-privilege account compromise.
- Segment the router management interface onto a dedicated VLAN accessible only to authorized administrators.
- Disable unused router services such as remote management, UPnP, and cloud-based administration features.
# Example: block inbound access to the router management port from untrusted segments
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -s <trusted_admin_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
