CVE-2026-3698 Overview
CVE-2026-3698 is a buffer overflow vulnerability in the UTT HiPER 810G router firmware up to version 1.7.7-171114. The flaw resides in the strcpy function call within the /goform/NTP endpoint. An authenticated remote attacker can manipulate input parameters to trigger a buffer overflow, leading to memory corruption and potential code execution on the device. The exploit details are publicly disclosed, increasing the likelihood of weaponization. The vulnerability is tracked under CWE-119 for improper restriction of operations within memory buffer bounds.
Critical Impact
Remote attackers with low-privilege access can corrupt memory on the router, potentially compromising network confidentiality, integrity, and availability.
Affected Products
- UTT HiPER 810G firmware versions up to 1.7.7-171114
- UTT 810G hardware revision 3.0
- All deployments exposing the /goform/NTP web management endpoint
Discovery Timeline
- 2026-03-08 - CVE-2026-3698 published to the National Vulnerability Database
- 2026-03-10 - Last updated in NVD database
Technical Details for CVE-2026-3698
Vulnerability Analysis
The vulnerability exists in the HTTP request handler for the /goform/NTP endpoint of the UTT HiPER 810G router. The handler processes Network Time Protocol (NTP) configuration parameters submitted through the web management interface. Input data is copied into a fixed-size stack buffer using the unsafe strcpy function without prior length validation. When attacker-supplied input exceeds the destination buffer size, adjacent memory is overwritten, including saved return addresses and stack frame pointers. This corruption enables an attacker to alter control flow within the embedded HTTP daemon. The router runs the affected service with elevated privileges, so successful exploitation yields execution in the context of the device management plane.
Root Cause
The root cause is the use of strcpy without bounds checking on attacker-controlled HTTP parameters. The function copies bytes until a null terminator is encountered, with no awareness of the destination buffer's allocated size. This pattern, classified as CWE-119, is a long-recognized anti-pattern in C-based embedded firmware. Safer alternatives such as strncpy or strlcpy with explicit length limits would prevent the overflow.
Attack Vector
The attack is delivered over the network through the router's HTTP management interface. An attacker requires low-privilege authentication to reach the /goform/NTP endpoint. Once authenticated, the attacker submits a crafted POST request containing an oversized parameter value targeting the vulnerable strcpy call. No user interaction is required. Public exploit documentation describing the request structure is referenced in the GitHub CVE-VUL repository and VulDB entry #349644.
No verified exploit code is available in this advisory. Refer to the public references for technical reproduction details.
Detection Methods for CVE-2026-3698
Indicators of Compromise
- Unexpected POST requests to /goform/NTP containing abnormally long parameter values
- HTTP daemon crashes, restarts, or watchdog-triggered reboots on UTT HiPER 810G devices
- Unauthenticated outbound connections from the router to attacker-controlled hosts following NTP configuration changes
- Unexpected modifications to NTP server configuration entries on the device
Detection Strategies
- Inspect web management traffic for requests to /goform/NTP with parameter lengths exceeding typical NTP server hostname sizes (~253 bytes)
- Correlate HTTP request anomalies with subsequent device reboot or service restart events in syslog
- Deploy network-based intrusion detection signatures matching oversized POST bodies targeting UTT goform endpoints
Monitoring Recommendations
- Forward router syslog output to a centralized log platform and alert on HTTP daemon crash or restart events
- Monitor management plane access logs for authentication from unexpected source IP ranges
- Track configuration drift on NTP settings and other web-managed parameters to identify unauthorized changes
How to Mitigate CVE-2026-3698
Immediate Actions Required
- Restrict access to the router web management interface to trusted administrative subnets using ACLs or firewall rules
- Disable remote WAN-side management on UTT HiPER 810G devices to prevent external access to /goform/NTP
- Rotate administrative credentials and enforce strong passwords to reduce the chance of low-privilege account compromise
- Audit existing NTP configuration entries on affected devices for unauthorized modifications
Patch Information
As of the last NVD update on 2026-03-10, no vendor patch has been published for UTT HiPER 810G firmware versions up to 1.7.7-171114. Monitor the VulDB advisory and UTT vendor channels for firmware updates. Until a fix is available, compensating controls described below are required.
Workarounds
- Place the router management interface behind a VPN, requiring tunnel authentication before reaching the web UI
- Segment the management network from user and guest networks using VLANs to limit lateral access to the device
- Consider replacing end-of-support UTT HiPER 810G hardware with actively maintained equivalents if no vendor patch becomes available
# Example: restrict access to router management interface via upstream firewall
# Replace 10.0.0.0/24 with your administrative management subnet
# Replace 192.0.2.1 with the router's management IP
iptables -A FORWARD -s 10.0.0.0/24 -d 192.0.2.1 -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d 192.0.2.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.0.2.1 -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.
