CVE-2026-18897: UTT HiPER 1250GW Buffer Overflow Flaw

CVE-2026-18897 Overview

CVE-2026-18897 is a stack-based buffer overflow vulnerability in the UTT HiPER 1250GW router, affecting firmware versions up to v3.2.7-210907-180535. The flaw resides in the strcpy call inside the /goform/getOneApConfTempEntry handler. An attacker can trigger the overflow by manipulating the tempName argument, corrupting the stack over the network. The weakness is classified under [CWE-119], improper restriction of operations within the bounds of a memory buffer. A public exploit has been disclosed, and the vendor did not respond to the coordinated disclosure attempt.

Critical Impact
Remote attackers with low-privilege access can overflow the stack through the tempName parameter, achieving arbitrary code execution or full compromise of the router's confidentiality, integrity, and availability.

Affected Products

UTT HiPER 1250GW router
Firmware versions up to and including v3.2.7-210907-180535
The /goform/getOneApConfTempEntry web management endpoint

Discovery Timeline

2026-08-05 - CVE-2026-18897 published to the National Vulnerability Database
2026-08-05 - Last updated in NVD database

Technical Details for CVE-2026-18897

Vulnerability Analysis

The vulnerability exists in the HTTP handler for /goform/getOneApConfTempEntry, which processes access point configuration template requests. The handler reads the tempName parameter from the request and copies it into a fixed-size stack buffer using strcpy. Because strcpy performs no length validation, a long tempName value overwrites adjacent stack memory, including saved return addresses and frame pointers.

Exploitation requires network reachability to the router's web management interface and low-privilege authentication. Successful exploitation grants attackers control over the router process, which typically runs with elevated privileges on embedded Linux devices. Compromise of the router yields a pivot point into the internal network and enables traffic interception, DNS manipulation, and lateral movement.

Root Cause

The root cause is the use of the unbounded strcpy function on attacker-controlled input without prior length validation. Standard defensive practice requires bounded copy routines such as strncpy or strlcpy, along with explicit input size checks. The affected firmware image also appears to lack modern exploit mitigations commonly missing on embedded MIPS or ARM routers, such as reliable stack canaries and full address space layout randomization.

Attack Vector

The attack traverses the network to reach the router's HTTP administration service. An authenticated attacker sends a crafted POST or GET request to /goform/getOneApConfTempEntry with an oversized tempName value. The oversized string overflows the stack buffer during the strcpy operation, allowing the attacker to hijack execution flow. A public proof-of-concept is referenced in the GitHub CVE Documentation and VulDB Vulnerability Details.

// Vulnerable pattern (conceptual)
// Actual exploit details are described in the referenced advisory
void getOneApConfTempEntry_handler(request *req) {
    char localBuffer[N];
    char *tempName = get_param(req, "tempName");
    strcpy(localBuffer, tempName); // No bounds check
}

Detection Methods for CVE-2026-18897

Indicators of Compromise

HTTP requests targeting /goform/getOneApConfTempEntry with abnormally long tempName values, particularly strings exceeding a few hundred bytes.
Unexpected reboots, watchdog resets, or crash log entries generated by the router's HTTP daemon following inbound web management traffic.
New or unfamiliar administrative sessions on the UTT HiPER 1250GW web console originating from external or untrusted subnets.

Detection Strategies

Inspect network telemetry for HTTP POST/GET traffic to /goform/ endpoints on UTT HiPER devices and alert on parameter payloads that exceed baseline sizes.
Correlate authentication events on the router with subsequent long-parameter requests to identify low-privilege accounts abused for exploitation.
Deploy IDS/IPS signatures that match on the URI substring getOneApConfTempEntry combined with a tempName value beyond a defined length threshold.

Monitoring Recommendations

Forward router syslog, HTTP access logs, and administrative audit events into a centralized data lake for retention and correlation.
Monitor egress traffic from the router itself for beaconing patterns that would indicate post-exploitation implants on the device.
Track firmware version inventory across managed sites and alert on any UTT HiPER 1250GW device running v3.2.7-210907-180535 or earlier.

How to Mitigate CVE-2026-18897

Immediate Actions Required

Restrict access to the router's web management interface so that it is reachable only from trusted management VLANs or jump hosts.
Rotate all administrative credentials on the UTT HiPER 1250GW and disable any unused low-privilege accounts that could be leveraged to reach the vulnerable endpoint.
Place the device behind a network access control list that blocks untrusted sources from reaching /goform/ URIs.

Patch Information

No vendor patch is available at the time of publication. According to the disclosure record on VulDB CVE Summary, the vendor was contacted early but did not respond. Organizations should track the vendor's advisory channels and apply firmware updates as soon as they are released.

Workarounds

Disable remote administration on WAN interfaces and permit management only over LAN or VPN.
Segment the router into a dedicated management network and enforce firewall rules blocking HTTP requests to /goform/getOneApConfTempEntry from unauthorized hosts.
Where feasible, replace end-of-support or unpatched UTT HiPER 1250GW devices with vendor-supported hardware that receives active security maintenance.

bash

# Example firewall rule blocking the vulnerable endpoint at an upstream gateway
iptables -I FORWARD -p tcp --dport 80 \
  -m string --string "/goform/getOneApConfTempEntry" --algo bm \
  -j DROP