CVE-2026-2935 Overview
CVE-2026-2935 is a buffer overflow vulnerability affecting UTT HiPER 810G routers running firmware versions up to 1.7.7-171114. The flaw resides in the strcpy function used by the /goform/ConfigExceptMSN endpoint. Attackers can manipulate the remark argument to trigger memory corruption over the network. A public exploit has been disclosed, increasing the likelihood of opportunistic attacks against exposed devices. The weakness is tracked under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Critical Impact
Remote attackers with valid high-privilege credentials can corrupt router memory through the remark parameter, potentially leading to arbitrary code execution or device compromise.
Affected Products
- UTT HiPER 810G firmware versions up to 1.7.7-171114
- UTT 810G hardware revision 3.0
- All deployments exposing the /goform/ConfigExceptMSN web management endpoint
Discovery Timeline
- 2026-02-22 - CVE-2026-2935 published to NVD
- 2026-02-24 - Last updated in NVD database
Technical Details for CVE-2026-2935
Vulnerability Analysis
The vulnerability exists in the web management interface of the UTT HiPER 810G router. When a request reaches /goform/ConfigExceptMSN, the handler copies the user-supplied remark parameter into a fixed-size stack buffer using strcpy. Because strcpy does not perform bounds checking, an oversized value overwrites adjacent stack memory.
Successful exploitation enables memory corruption that can crash the device or alter execution flow. The attack is reachable over the network, but the attacker must already hold high-privilege credentials on the device. Public availability of exploit details raises the risk of automated abuse against internet-exposed routers.
Root Cause
The root cause is the unsafe use of strcpy against attacker-controlled input in the ConfigExceptMSN handler. The function copies the remark argument into a stack buffer of fixed size without validating input length. This pattern is a textbook [CWE-119] memory boundary violation common in embedded firmware that reuses legacy C string routines.
Attack Vector
An authenticated remote attacker submits a crafted POST request to /goform/ConfigExceptMSN with an overlong remark field. The oversized string overflows the destination buffer during the strcpy operation. Depending on stack layout and protections present on the device, attackers may achieve denial of service or arbitrary code execution within the router's management context. No verified proof-of-concept code is reproduced here; refer to the GitHub CVE Issue Discussion for technical specifics.
Detection Methods for CVE-2026-2935
Indicators of Compromise
- Unexpected reboots, watchdog resets, or crashes of UTT HiPER 810G devices following administrative HTTP requests
- HTTP POST requests to /goform/ConfigExceptMSN containing abnormally long remark parameter values
- Unauthorized configuration changes to MSN exception or call-filtering settings on the router
Detection Strategies
- Inspect HTTP traffic to the router management interface for remark parameter values exceeding expected length thresholds
- Correlate authentication events with subsequent requests to /goform/ConfigExceptMSN to spot credential abuse
- Alert on repeated 5xx responses or session terminations from the management web server
Monitoring Recommendations
- Forward router syslog and management-plane HTTP logs to a centralized SIEM for analysis
- Baseline normal administrative behavior and flag deviations in form parameter sizes
- Monitor for outbound connections initiated by the router that deviate from operational baselines, which may indicate post-exploitation activity
How to Mitigate CVE-2026-2935
Immediate Actions Required
- Restrict access to the router's web management interface to trusted management VLANs or jump hosts
- Rotate administrative credentials and enforce strong, unique passwords on all UTT HiPER 810G devices
- Disable WAN-side access to the HTTP management service until a fixed firmware version is available
- Inventory all UTT HiPER 810G devices, capturing firmware version and exposure status
Patch Information
No vendor patch has been published in the referenced advisories at the time of NVD publication. Track the GitHub CVE Issue Discussion and VulDB entry 347297 for updates from UTT regarding fixed firmware releases.
Workarounds
- Place affected routers behind a perimeter firewall and block inbound HTTP/HTTPS to management ports
- Apply ACLs that permit management access only from a defined administrative subnet
- Where feasible, replace end-of-support UTT HiPER 810G units with vendor-supported hardware
# Configuration example: restrict management access to a trusted subnet
# Replace 10.0.10.0/24 with your administrative network
iptables -A INPUT -p tcp --dport 80 -s 10.0.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.0.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
