CVE-2026-9631 Overview
CVE-2026-9631 is a stack-based buffer overflow vulnerability affecting UTT HiPER 1250GW routers up to firmware version 3.2.7-210907-180535. The flaw resides in the strcpy function within /goform/formConfigFastDirectionW, part of the Web Management Interface. Attackers manipulate the Profile argument to overflow a fixed-size stack buffer. The vulnerability is exploitable remotely over the network, and a public exploit is now available. This weakness is categorized under [CWE-119], improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers with low privileges can trigger a stack-based buffer overflow in the router's web management interface, potentially leading to arbitrary code execution or denial of service on affected UTT HiPER 1250GW devices.
Affected Products
- UTT HiPER 1250GW router
- Firmware versions up to 3.2.7-210907-180535
- Web Management Interface component (/goform/formConfigFastDirectionW)
Discovery Timeline
- 2026-05-27 - CVE-2026-9631 published to NVD
- 2026-05-27 - Last updated in NVD database
Technical Details for CVE-2026-9631
Vulnerability Analysis
The vulnerability exists in the handler for /goform/formConfigFastDirectionW, a CGI endpoint exposed by the router's Web Management Interface. The handler uses strcpy to copy the user-supplied Profile parameter into a fixed-size stack buffer without performing length validation. Because strcpy copies until it encounters a null terminator, an attacker can supply an oversized Profile value that overruns the destination buffer.
The overflow corrupts adjacent stack memory, including saved return addresses and frame pointers. On embedded MIPS or ARM devices like the HiPER 1250GW, this typically enables control-flow hijacking through return address overwrite. Public exploit code referenced in the GitHub CVE Document demonstrates the attack against the affected formConfigFastDirectionW endpoint.
The EPSS score is 0.041%, indicating low predicted exploitation probability at the time of publication, despite the public proof of concept.
Root Cause
The root cause is the unsafe use of the strcpy function on attacker-controlled input. The web management firmware does not validate or bound-check the length of the Profile parameter before copying it into a stack-allocated buffer. This is a classic [CWE-119] memory safety violation common in legacy embedded web interfaces written in C.
Attack Vector
An authenticated attacker with low privileges sends a crafted HTTP POST request to /goform/formConfigFastDirectionW containing an oversized Profile parameter. The malformed request triggers the overflow during request processing in the web server. Because the endpoint is reachable over the network, exploitation does not require local access or user interaction. Successful exploitation impacts confidentiality, integrity, and availability of the router.
No verified exploit code is reproduced here. See the VulDB Vulnerability #365740 entry and the GitHub CVE Document for technical proof-of-concept details.
Detection Methods for CVE-2026-9631
Indicators of Compromise
- HTTP POST requests to /goform/formConfigFastDirectionW containing abnormally long Profile parameter values.
- Unexpected reboots, crashes, or unresponsive states in the HiPER 1250GW web management interface.
- Outbound connections from the router to unfamiliar external hosts following web interface activity.
- New or modified configuration entries on the router that do not match administrative change records.
Detection Strategies
- Inspect web server access logs on the router for requests targeting formConfigFastDirectionW with oversized POST bodies or Profile field values exceeding expected length.
- Deploy network intrusion detection signatures that flag HTTP requests to the vulnerable endpoint containing non-printable bytes or shellcode patterns.
- Monitor for HTTP requests to the router management interface originating from untrusted network segments.
Monitoring Recommendations
- Forward router syslog and HTTP request logs to a centralized logging platform for correlation and retention.
- Establish baselines for normal management interface traffic volume and alert on deviations.
- Track firmware version inventory across all UTT HiPER 1250GW units to identify devices running vulnerable builds up to 3.2.7-210907-180535.
How to Mitigate CVE-2026-9631
Immediate Actions Required
- Restrict access to the router's Web Management Interface to trusted management VLANs or specific administrative IP addresses only.
- Disable remote (WAN-side) management on UTT HiPER 1250GW devices until a vendor patch is available.
- Rotate administrative credentials on affected devices to limit risk from credential reuse combined with the low-privilege requirement.
- Audit router configurations and logs for signs of tampering or unauthorized access.
Patch Information
At the time of publication, no vendor advisory or patched firmware release for the UTT HiPER 1250GW has been linked in the NVD entry. Administrators should monitor the VulDB Vulnerability #365740 record and UTT vendor channels for an official firmware update addressing the strcpy flaw in formConfigFastDirectionW.
Workarounds
- Place affected routers behind a perimeter firewall and block external access to TCP ports used by the Web Management Interface.
- Use access control lists to permit management traffic only from designated administrator workstations.
- Where feasible, replace end-of-life or unpatched UTT HiPER 1250GW devices with supported alternatives that receive timely security updates.
- Segment IoT and network infrastructure devices onto isolated management networks to reduce lateral movement opportunities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
