CVE-2026-9628: UTT HiPER 1200GW Buffer Overflow Flaw

CVE-2026-9628 Overview

CVE-2026-9628 is a stack-based buffer overflow vulnerability affecting UTT HiPER 1200GW routers up to firmware version 2.5.3-170306. The flaw resides in an unknown function within /goform/formPptpClientConfig, part of the Web Management Interface. Attackers can trigger the overflow by manipulating the PPTP server address, username, password, or tunnel name arguments. The vulnerability is remotely exploitable and a public exploit has been disclosed, increasing the likelihood of attacks against exposed devices. The issue is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer).

Critical Impact
Authenticated remote attackers can overflow the stack via the PPTP client configuration endpoint, potentially leading to arbitrary code execution or device compromise on UTT HiPER 1200GW routers.

Affected Products

UTT HiPER 1200GW router firmware versions up to and including 2.5.3-170306
Web Management Interface component handling /goform/formPptpClientConfig
PPTP client configuration functionality within the affected firmware

Discovery Timeline

2026-05-27 - CVE-2026-9628 published to the National Vulnerability Database
2026-05-28 - Last updated in NVD database

Technical Details for CVE-2026-9628

Vulnerability Analysis

The vulnerability stems from improper bounds checking in the PPTP client configuration handler within the UTT HiPER 1200GW Web Management Interface. The /goform/formPptpClientConfig endpoint accepts user-supplied input for the PPTP server address, username, password, and tunnel name fields. The handler copies these values into fixed-size stack buffers without validating input length. Attackers can submit oversized values to overwrite adjacent stack memory, including saved return addresses and control flow structures.

Exploitation requires network access to the management interface and a low level of authentication privilege. Successful exploitation impacts confidentiality, integrity, and availability of the device. Public availability of the exploit lowers the barrier for attackers seeking to weaponize the flaw against exposed routers.

Root Cause

The root cause is the absence of input length validation in the function processing PPTP configuration parameters. The handler appears to use unsafe string copy operations such as strcpy or sprintf against fixed-size stack buffers. This pattern is consistent with [CWE-119] memory boundary violations common to embedded router firmware compiled without modern stack protections.

Attack Vector

The attack is initiated remotely across the network against the device's Web Management Interface. An attacker with low-privilege credentials submits a crafted HTTP request to /goform/formPptpClientConfig containing overlong values in one or more of the four vulnerable parameters. The oversized input overflows the destination buffer on the stack, corrupting saved registers and the return pointer. Depending on memory protections present in the firmware build, this can lead to denial of service or arbitrary code execution with the privileges of the web server process.

No verified proof-of-concept code is reproduced here. Refer to the GitHub CVE Documentation and VulDB Vulnerability #365684 for technical write-ups.

Detection Methods for CVE-2026-9628

Indicators of Compromise

HTTP POST requests to /goform/formPptpClientConfig containing abnormally long string values in the PPTP server address, username, password, or tunnel name fields
Unexpected reboots, crashes, or web management interface unavailability on UTT HiPER 1200GW devices
Outbound connections from the router to unexpected hosts following configuration changes to the PPTP client

Detection Strategies

Inspect web server access logs for requests targeting /goform/formPptpClientConfig with parameter values exceeding typical lengths
Deploy network-based intrusion detection signatures that flag HTTP requests containing oversized PPTP configuration parameters directed at router management interfaces
Monitor for repeated authentication attempts to the Web Management Interface that precede configuration endpoint access

Monitoring Recommendations

Audit administrative access to UTT HiPER 1200GW management interfaces and restrict access to trusted management networks
Alert on any internet-exposed administrative interfaces identified through external attack surface management
Log and review all configuration changes affecting PPTP client settings on edge routers

How to Mitigate CVE-2026-9628

Immediate Actions Required

Remove UTT HiPER 1200GW Web Management Interface exposure from untrusted networks, particularly the public internet
Restrict management interface access to a dedicated administrative VLAN or trusted source IP allowlist
Rotate administrative credentials and enforce strong, unique passwords on all affected devices
Inventory all UTT HiPER 1200GW devices running firmware 2.5.3-170306 or earlier

Patch Information

No vendor advisory or patched firmware release has been published in the available references at the time of CVE assignment. Monitor UTT vendor channels for an updated firmware release addressing the buffer overflow in /goform/formPptpClientConfig. Apply firmware updates immediately upon release.

Workarounds

Disable the Web Management Interface when not actively in use for administration
Place affected routers behind a firewall that blocks inbound HTTP/HTTPS traffic to the management port from external sources
Consider replacement of end-of-life or unpatched devices with supported networking equipment if no vendor fix becomes available
Segment affected routers from sensitive internal networks to limit blast radius if compromised

bash

# Example: restrict management interface access via upstream firewall (iptables)
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -s <trusted_admin_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -s <trusted_admin_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -j DROP