CVE-2026-3275: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-3275 Overview

CVE-2026-3275 is a buffer overflow vulnerability in the Tenda F453 router running firmware version 1.0.0.3. The flaw resides in the fromAddressNat function within the /goform/addressNat endpoint of the httpd component. An attacker can trigger the overflow by manipulating the entrys argument. The issue is reachable remotely over the network and requires only low privileges. Public disclosure of the exploit increases the likelihood 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 with low privileges can corrupt memory in the router's web server, potentially leading to denial of service or arbitrary code execution on the device.

Affected Products

Tenda F453 router (hardware)
Tenda F453 Firmware version 1.0.0.3
httpd component handling /goform/addressNat

Discovery Timeline

2026-02-27 - CVE-2026-3275 published to NVD
2026-02-27 - Last updated in NVD database

Technical Details for CVE-2026-3275

Vulnerability Analysis

The vulnerability affects the fromAddressNat function inside the embedded httpd web server on the Tenda F453. The function parses input from the /goform/addressNat handler, which is responsible for processing NAT (Network Address Translation) configuration entries submitted through the router's web interface. The entrys argument supplied by the requester is copied into a fixed-size stack or heap buffer without proper length validation. Once the attacker-controlled data exceeds the buffer's capacity, adjacent memory is overwritten. This memory corruption can crash the httpd process or be shaped to redirect execution flow on the device's MIPS or ARM-based platform.

Root Cause

The root cause is improper restriction of operations within the bounds of a memory buffer [CWE-119]. The fromAddressNat handler trusts the size of the entrys parameter and performs an unbounded copy operation. No input sanitization, length check, or safe string function guards the copy, which is a recurring pattern in Tenda's /goform/* request handlers.

Attack Vector

The attack vector is network-based. An authenticated user with low-level access to the router's web management interface can send a crafted POST request to /goform/addressNat containing an oversized entrys value. The request reaches the httpd process, which invokes fromAddressNat and triggers the overflow. Exploitation does not require user interaction. According to the EPSS data, the probability of exploitation in the next 30 days is 0.037% (11th percentile), but a public proof of concept has been released, raising risk for internet-exposed devices.

No verified exploit code is reproduced here. Refer to the GitHub Vulnerability Repository and VulDB entry #347999 for technical analysis of the request structure.

Detection Methods for CVE-2026-3275

Indicators of Compromise

Unexpected restarts or crashes of the httpd process on Tenda F453 devices
HTTP POST requests to /goform/addressNat containing abnormally long entrys parameters
Inbound web management traffic from external IP addresses to the router's administrative interface
Sudden loss of NAT functionality or configuration corruption on the device

Detection Strategies

Inspect web server access logs for requests to /goform/addressNat with payload sizes exceeding expected NAT entry lengths
Deploy network IDS signatures that flag oversized parameter values targeting Tenda /goform/* endpoints
Monitor router availability and reboot frequency as indicators of repeated exploitation attempts

Monitoring Recommendations

Forward router syslog data and HTTP request metadata to a centralized analytics platform for behavioral analysis
Alert on any administrative HTTP access originating from untrusted networks or non-management VLANs
Track outbound connections from the router itself, since successful code execution may turn the device into a pivot point

How to Mitigate CVE-2026-3275

Immediate Actions Required

Restrict access to the router's web management interface to trusted internal hosts only
Disable remote (WAN-side) administration on the Tenda F453
Change default and weak administrative credentials to reduce abuse of the low-privilege requirement
Segment vulnerable routers from sensitive network zones until a patch is applied

Patch Information

No vendor patch has been published in the available references at the time of CVE assignment. Monitor the Tenda Security Page for firmware updates addressing the fromAddressNat handler in versions above 1.0.0.3. Until a fixed firmware is released, treat all Tenda F453 deployments running 1.0.0.3 as exposed.

Workarounds

Block external access to TCP ports hosting the router's httpd service at the perimeter firewall
Apply ACLs that allow /goform/addressNat requests only from a dedicated management workstation
Replace affected devices with supported hardware if no firmware update becomes available

bash

# Example: restrict router admin interface to a single management host using iptables on an upstream gateway
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -s 10.10.10.5 -j ACCEPT
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -j DROP