CVE-2026-6988: Tenda HG10 Buffer Overflow Vulnerability

CVE-2026-6988 Overview

A buffer overflow vulnerability has been discovered in Tenda HG10 router firmware (HG7_HG9_HG10re_300001138_en_xpon). This critical flaw affects the formRoute function within the /boaform/formRouting endpoint of the Boa Service component. By manipulating the nextHop argument, an authenticated remote attacker can trigger a buffer overflow condition, potentially leading to arbitrary code execution or denial of service on the affected device.

Critical Impact

Remote attackers with low privileges can exploit this buffer overflow to potentially gain complete control of the affected Tenda HG10 router, compromising network security and enabling further attacks on connected devices.

Affected Products

• Tenda HG10 Firmware version 300001138
• Tenda HG10 Hardware Device
• Tenda HG7/HG9/HG10 Series (xpon variant)

Discovery Timeline

• 2026-04-25 - CVE-2026-6988 published to NVD
• 2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-6988

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the Boa web server service running on Tenda HG10 devices, specifically within the routing configuration functionality.

The formRoute function fails to properly validate the length of user-supplied input for the nextHop parameter before copying it into a fixed-size buffer. This boundary checking failure allows an attacker to supply an oversized value that overflows the allocated memory region, potentially overwriting adjacent memory structures including return addresses and function pointers.

The vulnerability is accessible over the network through the device's web management interface, requiring only low-level authentication to exploit. A proof-of-concept has been publicly documented, increasing the urgency for remediation.

Root Cause

The root cause of this vulnerability is insufficient input validation in the formRoute function when processing the nextHop routing parameter. The function accepts user-controlled data from HTTP POST requests to /boaform/formRouting without verifying that the input length does not exceed the destination buffer capacity.

This is a common firmware vulnerability pattern where embedded device manufacturers fail to implement proper bounds checking on web interface parameters, resulting in exploitable memory corruption conditions.

Attack Vector

The attack vector is network-based, targeting the Boa web server running on exposed Tenda HG10 devices. An attacker can craft a malicious HTTP POST request to the /boaform/formRouting endpoint with an oversized nextHop parameter value. The attack requires low-level authentication (typically default or weak credentials on consumer routers) but no user interaction.

Successful exploitation could allow the attacker to:

• Crash the Boa service causing denial of service
• Overwrite critical memory structures to redirect execution flow
• Achieve arbitrary code execution with the privileges of the Boa service
• Potentially gain persistent access to the device firmware

The vulnerability mechanism involves sending an HTTP POST request to the affected endpoint with a crafted nextHop parameter containing data that exceeds the expected buffer size. When the formRoute function processes this input, the overflow occurs, corrupting adjacent memory. Technical details and proof-of-concept information are available in the GitHub PoC Repository.

Detection Methods for CVE-2026-6988

Indicators of Compromise

• Unusual HTTP POST requests to /boaform/formRouting with abnormally large nextHop parameter values
• Unexpected Boa service crashes or restarts on Tenda HG10 devices
• Anomalous network traffic patterns originating from the router management interface
• Device instability or unexpected configuration changes

Detection Strategies

• Implement network intrusion detection rules to identify oversized POST requests to Boa web server endpoints
• Monitor for HTTP traffic containing /boaform/formRouting with parameters exceeding normal length thresholds
• Deploy application-layer firewalls to inspect and filter malformed requests to router management interfaces
• Enable logging on network boundary devices to capture attempts to access router administration pages

Monitoring Recommendations

• Restrict management interface access to trusted networks only using firewall rules
• Implement network segmentation to isolate IoT and network infrastructure devices
• Use SentinelOne Singularity for network traffic analysis to detect exploitation attempts
• Regularly audit device logs for authentication anomalies and service disruptions

How to Mitigate CVE-2026-6988

Immediate Actions Required

• Disable remote management access to Tenda HG10 devices immediately
• Restrict access to the web management interface to trusted internal IP addresses only
• Change default credentials to strong, unique passwords
• Monitor affected devices for signs of compromise or unusual behavior
• Consider network isolation for vulnerable devices until patched

Patch Information

No official patch information is currently available from Tenda. Users should monitor the Tenda Official Website for firmware updates addressing this vulnerability. Given the publicly available proof-of-concept, immediate implementation of workarounds is strongly recommended.

For tracking purposes, refer to the VulDB Vulnerability Entry #359540 for the latest status updates.

Workarounds

• Implement access control lists (ACLs) to restrict management interface access to specific trusted IP addresses
• Deploy a firewall rule to block external access to port 80/443 on the router's management interface
• Consider placing the device behind a more secure gateway with proper intrusion prevention capabilities
• If feasible, disable the Boa web server service until a patch is available
• Monitor for firmware updates from Tenda and apply immediately when released

# Example iptables rule to restrict management access (apply on upstream firewall)
# Block external access to Tenda HG10 management interface
iptables -A FORWARD -d <TENDA_HG10_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <TENDA_HG10_IP> -p tcp --dport 443 -j DROP
# Allow only trusted management network
iptables -I FORWARD -s <TRUSTED_MGMT_NETWORK> -d <TENDA_HG10_IP> -p tcp --dport 80 -j ACCEPT