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The vulnerability CVE-2026-3815 is a critical buffer overflow found in the UTT HiPER 810G gigabit router, specifically in firmware versions up to 1.7.7-1711. The flaw exists within the `strcpy` function in the web management interface file located at /goform/formApMail. The `strcpy` function is inherently unsafe because it does not perform bounds checking on the length of data being copied. By sending a specially crafted HTTP POST request to this endpoint with an excessively long value for a specific parameter (likely related to email alert configuration), an attacker can overflow the fixed-size buffer in memory. This corruption of memory can lead to an immediate denial-of-service (device crash/reboot) or, more critically, allow the attacker to overwrite adjacent memory regions to hijack the program’s control flow. Because the device does not implement modern memory protection techniques like ASLR or stack canaries in this context, a remote, unauthenticated attacker can potentially execute arbitrary code with root privileges, completely compromising the router .
dailycve form:
Platform: UTT HiPER 810G
Version: up to 1.7.7-1711
Vulnerability : Buffer Overflow
Severity: Critical (8.8 CVSS)
date: March 9, 2026
Prediction: March 2027
What Undercode Say:
Analytics:
The vulnerability is caused by the use of the unsafe C function `strcpy()` in the web handler /goform/formApMail. It allows for Remote Code Execution (RCE) due to the lack of stack canaries and ASLR in the firmware. A public Proof-of-Concept (PoC) exploit is available on GitHub, increasing the risk of mass exploitation by botnets (e.g., Mirai variants) targeting network infrastructure .
Exploit:
Attackers can exploit this by sending a crafted POST request. The following is a conceptual example of how the buffer overflow is triggered:
Conceptual Bash script using curl to demonstrate the overflow
Assumes the router's IP is 192.168.1.1
TARGET="http://192.168.1.1/goform/formApMail"
A long string of "A"s to overflow the buffer and cause a crash
PAYLOAD=$(python3 -c 'print("A" 1000)')
echo "Sending malicious payload to $TARGET"
curl -X POST $TARGET \
-d "param1=value1¶m2=$PAYLOAD" \
--connect-timeout 5
echo "If the router crashes or reboots, it is vulnerable."
Protection from this CVE:
- Firmware Update: Check the official UTT (Shanghai UTT Technologies) website for a patched firmware version that replaces `strcpy` with safe functions like `strncpy` or `strlcpy` .
- Network Segmentation: Isolate the management interface of the router from the public internet and untrusted networks. Restrict access to the web interface (ports 80/443) to only trusted internal IP addresses via firewall rules.
- Monitor Logs: Monitor for unusual HTTP requests to `/goform/formApMail` containing excessively long strings or non-printable characters indicative of shellcode.
Impact:
Successful exploitation leads to complete system compromise. An attacker can gain root shell access, allowing them to monitor all network traffic (sniffing credentials), add the router to a botnet for DDoS attacks, modify DNS settings to redirect users to phishing sites, and deploy persistent malware inside the firmware.
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Sources:
Reported By: nvd.nist.gov
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