CVE-2025-70998: UTT 810 Firmware Auth Bypass Vulnerability

CVE-2025-70998 Overview

CVE-2025-70998 is a critical insecure default configuration vulnerability affecting UTT HiPER 810 / nv810v4 router firmware version 1.5.0-140603. The firmware ships with insecure default credentials for the telnet service, enabling remote attackers to potentially gain root access to the device via crafted scripts. This weakness (CWE-1188: Insecure Default Initialization of Resource) represents a severe security risk for any network relying on these devices.

Critical Impact

Remote attackers can exploit hardcoded default credentials in the telnet service to gain unauthorized root access, potentially leading to full device compromise, network pivoting, and persistent unauthorized access.

Affected Products

• UTT 810 Firmware version 1.5.0-140603
• UTT HiPER 810 Hardware revision 4.0
• UTT nv810v4 Router

Discovery Timeline

• 2026-02-18 - CVE-2025-70998 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2025-70998

Vulnerability Analysis

This vulnerability stems from the use of insecure default credentials in the telnet service of the UTT HiPER 810 / nv810v4 router firmware. The telnet service, when enabled, accepts authentication using pre-configured credentials that are either widely known, easily guessable, or publicly documented. Since telnet transmits data in cleartext, the combination of insecure defaults and an unencrypted protocol creates multiple attack surfaces.

The firmware's failure to enforce credential changes during initial setup or to disable remote management services by default significantly increases exposure. Attackers who successfully authenticate gain root-level access to the underlying Linux operating system, providing complete control over the device's configuration, traffic routing, and connected network segments.

Root Cause

The root cause of CVE-2025-70998 is CWE-1188 (Insecure Default Initialization of Resource). The firmware initializes the telnet service with default credentials that are either hardcoded or set to commonly known values without requiring users to change them before deployment. This design flaw bypasses fundamental security principles of defense-in-depth and least privilege.

Attack Vector

The attack vector for this vulnerability is network-based and requires no user interaction or prior authentication. An attacker with network access to the device's telnet port (typically TCP port 23) can attempt authentication using known default credentials. The attack flow typically involves:

1. Scanning the network for devices exposing the telnet service
2. Identifying UTT HiPER 810 / nv810v4 devices through banner grabbing or fingerprinting
3. Authenticating using documented default credentials
4. Executing arbitrary commands with root privileges

Further technical details regarding the exploitation mechanism and proof-of-concept are available in the GitHub PoC Repository.

Detection Methods for CVE-2025-70998

Indicators of Compromise

• Unexpected telnet sessions or connections to port 23 from external IP addresses
• Authentication logs showing successful logins using default usernames on router devices
• New or modified user accounts on router firmware
• Configuration changes or firmware modifications not authorized by administrators
• Unusual outbound network traffic originating from the router device

Detection Strategies

• Monitor network traffic for telnet connections (TCP port 23) to UTT HiPER 810 devices
• Implement network intrusion detection rules to flag authentication attempts using known default credentials
• Deploy endpoint detection to identify scripted or automated telnet connection attempts
• Perform regular configuration audits comparing current device settings against baseline configurations

Monitoring Recommendations

• Enable logging on all network management interfaces and forward logs to a SIEM solution
• Configure alerts for any successful telnet authentication events
• Monitor for firmware modification or configuration export activities
• Implement network segmentation to isolate IoT and network infrastructure devices

How to Mitigate CVE-2025-70998

Immediate Actions Required

• Change all default credentials on UTT HiPER 810 / nv810v4 devices immediately
• Disable the telnet service if not required for device management
• Restrict access to management interfaces using firewall rules or ACLs
• Segment network infrastructure devices from general user networks
• Audit all UTT router devices in your environment for this firmware version

Patch Information

At the time of publication, no vendor patch or security advisory has been released by UTT. Organizations should monitor the vendor's official channels for firmware updates addressing this vulnerability. In the absence of an official patch, implementing the workarounds below is strongly recommended.

For additional technical details, refer to the GitHub PoC Repository.

Workarounds

• Disable telnet service entirely and use SSH if available for remote management
• Implement strong, unique passwords for all device accounts
• Configure firewall rules to block external access to telnet port (TCP 23)
• Use network segmentation to limit exposure of vulnerable devices
• Consider replacing end-of-life devices with actively supported alternatives

# Example firewall rule to block external telnet access (iptables)
iptables -A INPUT -p tcp --dport 23 -s 0.0.0.0/0 -j DROP

# Allow telnet only from specific management subnet
iptables -A INPUT -p tcp --dport 23 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 23 -j DROP