CVE-2026-4553: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-4553 Overview

CVE-2026-4553 is a stack-based buffer overflow vulnerability in the Tenda F453 router running firmware version 1.0.0.3. The flaw resides in the fromNatlimit function within the /goform/Natlimit endpoint, which belongs to the Parameters Handler component. Manipulation of the page argument triggers the overflow condition. Attackers can reach the vulnerable function over the network, and a public exploit description is available. The weakness is classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer).

Critical Impact
Remote attackers with low-level authentication can corrupt stack memory on the router, leading to potential code execution and full compromise of the device's confidentiality, integrity, and availability.

Affected Products

Tenda F453 router (hardware)
Tenda F453 firmware version 1.0.0.3
Devices exposing the /goform/Natlimit management endpoint

Discovery Timeline

2026-03-22 - CVE-2026-4553 published to NVD
2026-04-02 - Last updated in NVD database

Technical Details for CVE-2026-4553

Vulnerability Analysis

The vulnerability exists in the fromNatlimit function exposed through the /goform/Natlimit HTTP handler on the Tenda F453 web management interface. The function processes the page parameter without enforcing proper bounds checking before copying its contents onto a fixed-size stack buffer. Sending an overly long page value overruns the buffer and corrupts adjacent stack memory, including saved return addresses. Successful exploitation can divert execution flow on the embedded MIPS/ARM target, enabling arbitrary code execution within the context of the router's web server process. Because the router operates as a network gateway, compromise allows attackers to intercept traffic, pivot into internal networks, or persistently modify device behavior.

Root Cause

The root cause is improper input validation on a user-supplied query or POST parameter. The fromNatlimit handler copies the page argument into a stack buffer using an unsafe string operation that does not validate the source length against the destination capacity, matching the [CWE-119] pattern common across Tenda goform handlers.

Attack Vector

The attack is delivered remotely over the network against the router's HTTP management interface. The CVSS vector indicates low attack complexity and requires low privileges, meaning an attacker needs basic authenticated access to the web UI. No user interaction is required to trigger the overflow once a crafted request is submitted to /goform/Natlimit.

No verified proof-of-concept code is included here. Technical details and a public write-up are referenced in the GitHub PoC Repository and VulDB entry #352380.

Detection Methods for CVE-2026-4553

Indicators of Compromise

HTTP POST or GET requests to /goform/Natlimit containing abnormally long page parameter values
Unexpected restarts, crashes, or watchdog reboots of the Tenda F453 router
Outbound connections from the router to unfamiliar IP addresses following management interface activity
New or modified NAT, firewall, or DNS configurations not originating from administrative actions

Detection Strategies

Inspect HTTP request bodies and query strings on management traffic for page parameters exceeding expected length thresholds
Deploy network IDS signatures targeting the /goform/Natlimit URI combined with oversized parameter payloads
Correlate router authentication events with subsequent crash or reboot telemetry to surface exploitation attempts

Monitoring Recommendations

Restrict and log all access to the router's HTTP management interface and forward logs to a centralized analytics platform
Monitor for repeated POSTs to /goform/ endpoints from a single source, which often indicates fuzzing or exploit attempts
Alert on configuration changes to NAT and routing tables outside approved change windows

How to Mitigate CVE-2026-4553

Immediate Actions Required

Disable remote (WAN-side) administration on the Tenda F453 and limit management access to trusted LAN segments only
Change default and weak administrative credentials to reduce the pool of low-privilege actors that can reach the vulnerable handler
Place affected routers behind a network segment with strict ACLs until a vendor patch is verified and deployed

Patch Information

No official vendor advisory or firmware patch from Tenda has been published in the referenced sources at the time of this writing. Consult the Tenda Official Website for firmware updates beyond version 1.0.0.3, and review the VulDB entry for tracking advisory status.

Workarounds

Block external access to the router's HTTP/HTTPS management ports at the upstream firewall
Apply web application firewall or reverse-proxy rules that reject requests to /goform/Natlimit containing page values over a conservative byte limit
Where business requirements permit, replace end-of-life or unpatched Tenda F453 units with currently supported hardware

bash

# Example iptables rules to restrict router management access to an admin subnet
iptables -A INPUT -p tcp --dport 80  -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80  -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP