CVE-2026-4862 Overview
CVE-2026-4862 is a buffer overflow vulnerability in the UTT HiPER 1250GW router through firmware version 3.2.7-210907-180535. The flaw resides in the strcpy call within the /goform/formConfigDnsFilterGlobal endpoint of the Parameter Handler component. Attackers can trigger the overflow by submitting a crafted GroupName argument over the network. The exploit has been publicly disclosed and may be used by attackers. The weakness is classified under CWE-119, improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers with low-privileged access can corrupt router memory through the GroupName parameter, enabling potential code execution and full device compromise.
Affected Products
- UTT HiPER 1250GW router
- Firmware versions up to and including 3.2.7-210907-180535
- Parameter Handler component handling /goform/formConfigDnsFilterGlobal
Discovery Timeline
- 2026-03-26 - CVE-2026-4862 published to NVD
- 2026-04-24 - Last updated in NVD database
Technical Details for CVE-2026-4862
Vulnerability Analysis
The vulnerability exists in the firmware's web management interface, specifically in the handler responsible for DNS filter group configuration. When a request reaches /goform/formConfigDnsFilterGlobal, the firmware processes the GroupName HTTP parameter and copies it into a fixed-size stack buffer using strcpy. Because strcpy performs no bounds checking, an oversized GroupName value overwrites adjacent stack memory, including saved registers and return addresses.
The Common Weakness Enumeration classification [CWE-119] reflects the lack of buffer boundary validation. Successful exploitation can lead to arbitrary code execution within the router process context, denial of service through device crash, or persistent control over the affected device.
Root Cause
The root cause is the use of the unbounded strcpy function on attacker-controlled input. The firmware accepts the GroupName parameter directly from the HTTP request and passes it to strcpy without verifying its length against the destination buffer size. The Parameter Handler component does not apply input length validation or use a safer alternative such as strncpy or strlcpy.
Attack Vector
An authenticated attacker on the network reachable by the router can issue an HTTP POST request to /goform/formConfigDnsFilterGlobal containing an oversized GroupName value. The request requires low privileges and no user interaction. Because routers commonly expose their management interface on the LAN and sometimes on the WAN, the attack surface includes both adjacent and internet-facing deployments.
No verified proof-of-concept code is published in the enriched data. The vulnerability mechanism is documented in the GitHub IoT Vulnerabilities Document and tracked in VulDB entry #353193.
Detection Methods for CVE-2026-4862
Indicators of Compromise
- HTTP POST requests to /goform/formConfigDnsFilterGlobal containing abnormally long GroupName parameter values
- Unexpected reboots, crashes, or web management interface unavailability on UTT HiPER 1250GW devices
- Outbound connections from the router to unfamiliar hosts after configuration requests
- New or modified DNS filter group entries that were not authorized by administrators
Detection Strategies
- Inspect HTTP traffic to the router management interface and alert on requests where GroupName exceeds expected length thresholds.
- Monitor router syslog for crash signatures, watchdog resets, or process restarts following configuration requests.
- Baseline normal administrative traffic patterns and flag deviations targeting /goform/ endpoints.
Monitoring Recommendations
- Forward router syslog and HTTP access logs to a centralized SIEM for correlation across network devices.
- Track authentication events on the router management interface to identify credential abuse preceding exploitation.
- Apply network intrusion detection signatures that match oversized parameters submitted to the formConfigDnsFilterGlobal endpoint.
How to Mitigate CVE-2026-4862
Immediate Actions Required
- Restrict access to the router web management interface to trusted management VLANs or specific administrative IP addresses.
- Disable WAN-side management access until a firmware update is available from UTT.
- Rotate administrative credentials for the device to reduce the value of any captured low-privilege accounts.
- Inventory all UTT HiPER 1250GW devices in the environment and confirm firmware versions against 3.2.7-210907-180535.
Patch Information
No vendor patch is referenced in the available advisory data. Administrators should monitor UTT vendor channels and the VulDB record for CVE-2026-4862 for updated firmware. Until a fix is released, network-level controls remain the primary defense.
Workarounds
- Place affected routers behind a separate firewall and block external access to TCP ports serving the management UI.
- Use access control lists to limit which internal hosts can reach /goform/formConfigDnsFilterGlobal.
- Replace affected devices with patched alternatives in high-risk segments such as DMZ or remote office gateways.
- Apply web application firewall rules upstream of the router to drop requests with oversized GroupName parameters.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
