CVE-2026-3699 Overview
CVE-2026-3699 is a buffer overflow vulnerability affecting UTT HiPER 810G routers running firmware versions up to 1.7.7-171114. The flaw resides in the strcpy function call within the /goform/formRemoteControl endpoint. Attackers can trigger the overflow remotely over the network with low privileges, leading to memory corruption and potential code execution on the device. Public exploit details have been released, increasing the risk of opportunistic attacks against exposed devices. The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Critical Impact
Remote attackers can corrupt memory on UTT HiPER 810G routers through the /goform/formRemoteControl endpoint, with public exploit information available.
Affected Products
- UTT HiPER 810G firmware versions up to 1.7.7-171114
- UTT HiPER 810G hardware (version 3.0)
- Network deployments exposing the web management interface
Discovery Timeline
- 2026-03-08 - CVE-2026-3699 published to NVD
- 2026-03-10 - Last updated in NVD database
Technical Details for CVE-2026-3699
Vulnerability Analysis
The vulnerability resides in the HTTP handler bound to the /goform/formRemoteControl endpoint of the UTT HiPER 810G router firmware. The handler invokes strcpy to copy attacker-controlled data from an HTTP request parameter into a fixed-size stack or heap buffer without validating the input length. When the supplied data exceeds the destination buffer size, adjacent memory is overwritten, leading to memory corruption. Depending on the surrounding context, this corruption can overwrite saved return addresses, function pointers, or control structures, enabling arbitrary code execution on the embedded device.
Successful exploitation grants control over the network gateway, allowing traffic interception, lateral movement, and persistent compromise of the routed network. The endpoint is reachable over the network and requires only low-level credentials to invoke.
Root Cause
The root cause is the unsafe use of strcpy without bounds checking on user-controlled HTTP request data. The formRemoteControl handler trusts the length of incoming parameter values, copying them directly into a fixed-size buffer. This pattern is a textbook [CWE-119] memory boundary violation common in legacy embedded web management interfaces written in C.
Attack Vector
An authenticated attacker sends a crafted HTTP POST request to /goform/formRemoteControl containing an oversized parameter value. The web server invokes the vulnerable strcpy operation, overflowing the destination buffer. The attack requires network reachability to the router's management interface and low-level credentials. No user interaction is required. Devices exposing the management interface to the WAN face heightened risk.
No verified proof-of-concept code is available in the public references. Technical details are described in the GitHub CVE Vulnerability Report and the VulDB advisory.
Detection Methods for CVE-2026-3699
Indicators of Compromise
- HTTP POST requests to /goform/formRemoteControl containing abnormally long parameter values
- Unexpected reboots, crashes, or service restarts of the router web management daemon
- Outbound connections from the router to unfamiliar external hosts indicating post-exploitation activity
- New or modified firewall rules, DNS settings, or administrative accounts on the device
Detection Strategies
- Inspect web server access logs for requests to /goform/formRemoteControl with payload sizes that exceed expected parameter lengths
- Deploy network intrusion detection signatures matching oversized POST bodies targeting the formRemoteControl URI
- Monitor for anomalous configuration changes on UTT HiPER 810G devices through SNMP or syslog forwarding
- Compare device firmware hashes against known-good baselines to detect tampering
Monitoring Recommendations
- Forward router syslog and authentication events to a centralized logging or SIEM platform for correlation
- Establish alerting on management interface access from non-administrative source networks
- Track DNS queries and outbound flows originating from the router for behavioral anomalies
- Audit administrative access patterns and flag credential use outside expected operational windows
How to Mitigate CVE-2026-3699
Immediate Actions Required
- Restrict access to the router management interface to trusted administrative networks only
- Disable WAN-side access to the web management interface if currently exposed
- Rotate all administrative credentials on affected UTT HiPER 810G devices
- Inventory all UTT HiPER 810G deployments running firmware up to 1.7.7-171114 and isolate vulnerable units
Patch Information
No vendor patch has been referenced in the available advisory data. Operators should consult UTT directly for firmware updates addressing this issue and monitor the VulDB entry for updates. Where remediation is not available, network-level compensating controls must be enforced.
Workarounds
- Place affected routers behind a firewall and block external access to TCP/80 and TCP/443 on the management interface
- Implement an access control list permitting management connections only from a dedicated jump host or admin VLAN
- Replace end-of-life UTT HiPER 810G devices with supported hardware where vendor patches are not forthcoming
- Enable network segmentation to limit the blast radius if a device is compromised
# Example: Restrict management interface access using upstream firewall ACL
# Permit only the admin subnet 10.10.50.0/24 to reach the router management IP
iptables -A FORWARD -s 10.10.50.0/24 -d <router_mgmt_ip> -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d <router_mgmt_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_mgmt_ip> -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
