CVE-2026-13517 Overview
CVE-2026-13517 is a stack-based buffer overflow vulnerability in the Tenda JD12L router running firmware version 16.03.53.23. The flaw resides in the formWifiBasicSet function within the /goform/WifiBasicSet endpoint. Attackers can trigger the overflow by manipulating the security_5g argument. The issue is classified under CWE-119, covering improper restriction of operations within the bounds of a memory buffer. Exploitation can be performed remotely over the network, and a public exploit has been released, increasing the risk of opportunistic attacks against exposed devices.
Critical Impact
Remote attackers with low-privilege access can corrupt stack memory on affected Tenda JD12L routers, potentially leading to code execution or device compromise.
Affected Products
- Tenda JD12L router
- Firmware version 16.03.53.23
- formWifiBasicSet function in /goform/WifiBasicSet
Discovery Timeline
- 2026-06-29 - CVE-2026-13517 published to NVD
- 2026-06-29 - Last updated in NVD database
Technical Details for CVE-2026-13517
Vulnerability Analysis
The vulnerability affects the formWifiBasicSet handler in the Tenda JD12L web management interface. This handler processes wireless configuration requests submitted to the /goform/WifiBasicSet endpoint. The security_5g parameter, which specifies the 5 GHz wireless security mode, is copied into a fixed-size stack buffer without proper length validation. When an attacker supplies an oversized value, the copy operation writes past the buffer boundary and overwrites adjacent stack memory, including saved return addresses.
An EPSS score of 0.466% reflects a low but non-trivial probability of exploitation attempts in the near term. However, the presence of a published proof-of-concept significantly raises the practical risk for exposed devices.
Root Cause
The root cause is the absence of bounds checking when the formWifiBasicSet function processes the security_5g HTTP parameter. The function uses unsafe string handling routines that trust attacker-controlled input length. This pattern is common across the Tenda /goform/ interface family, where user-supplied form values are copied directly into stack-allocated buffers.
Attack Vector
Exploitation requires network access to the router's management interface and low-level authenticated privileges. An attacker crafts an HTTP POST request to /goform/WifiBasicSet containing an oversized security_5g field. The malformed value corrupts the call stack, and a carefully constructed payload can redirect execution to attacker-supplied shellcode or gadgets, leading to arbitrary code execution on the router with device privileges.
No verified code example is publicly available for republication. Refer to the GitHub Issue Discussion and VulDB CVE-2026-13517 for technical write-ups.
Detection Methods for CVE-2026-13517
Indicators of Compromise
- HTTP POST requests to /goform/WifiBasicSet containing unusually long security_5g parameter values.
- Unexpected reboots, crashes, or watchdog resets on Tenda JD12L devices following inbound management traffic.
- New or unknown outbound connections originating from the router after receiving crafted wireless configuration requests.
Detection Strategies
- Inspect web server and management interface logs for repeated or malformed requests to /goform/WifiBasicSet.
- Deploy network intrusion detection signatures that flag HTTP request bodies containing oversized security_5g values against Tenda management endpoints.
- Correlate router crash events with prior HTTP traffic to identify probable exploitation attempts.
Monitoring Recommendations
- Monitor management-plane traffic to embedded devices from untrusted VLANs or the internet.
- Track firmware version inventory to identify all Tenda JD12L units running 16.03.53.23.
- Alert on any exposure of router management interfaces to WAN-facing IP addresses.
How to Mitigate CVE-2026-13517
Immediate Actions Required
- Restrict access to the router's web management interface to trusted management VLANs only.
- Disable WAN-side administrative access on all Tenda JD12L devices.
- Rotate administrative credentials to reduce risk from low-privilege attackers gaining access.
- Isolate affected devices in a segmented network until a vendor patch is available.
Patch Information
At the time of publication, no official vendor patch has been referenced for CVE-2026-13517. Monitor the Tenda Official Website for firmware updates addressing the formWifiBasicSet stack overflow. Apply firmware updates immediately once released.
Workarounds
- Block external access to /goform/WifiBasicSet at an upstream firewall or reverse proxy.
- Enforce strong administrative authentication and disable default credentials on all affected routers.
- Replace end-of-life or unsupported Tenda JD12L devices with a supported model if no patch becomes available.
# Example: block WAN access to the Tenda management interface at an upstream firewall
iptables -A FORWARD -i wan0 -p tcp --dport 80 -d <router_ip> -j DROP
iptables -A FORWARD -i wan0 -p tcp --dport 443 -d <router_ip> -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
