CVE-2025-8160 Overview
CVE-2025-8160 is a buffer overflow vulnerability affecting Tenda AC20 wireless routers running firmware up to version 16.03.08.12. The flaw resides in the httpd component, specifically in the handler for the /goform/SetSysTimeCfg endpoint. Attackers can trigger the overflow by manipulating the timeZone argument, leading to memory corruption [CWE-119]. The vulnerability is remotely exploitable over the network and public disclosure of the exploit details has occurred through VulDB and a GitHub repository.
Critical Impact
Remote attackers with low privileges can corrupt memory through the timeZone parameter, potentially achieving arbitrary code execution on affected Tenda AC20 routers.
Affected Products
- Tenda AC20 router (hardware)
- Tenda AC20 firmware versions up to and including 16.03.08.12
- The vulnerable httpd component handling /goform/SetSysTimeCfg
Discovery Timeline
- 2025-07-25 - CVE-2025-8160 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-8160
Vulnerability Analysis
The vulnerability is a classic buffer overflow [CWE-119] in the httpd web management daemon of the Tenda AC20 router. The flaw is reachable through the /goform/SetSysTimeCfg endpoint, which configures system time settings on the device. The handler accepts a timeZone parameter from HTTP requests and copies it into a fixed-size stack or heap buffer without enforcing length boundaries.
Exploitation requires network access to the router's web management interface and low-level authenticated context. Successful exploitation can corrupt adjacent memory structures, overwrite return addresses, and redirect execution. On embedded MIPS or ARM-based routers like the AC20, this typically leads to arbitrary code execution as the httpd process, which often runs with root privileges.
Root Cause
The root cause is the absence of input length validation on the timeZone argument before it is written into a fixed-size buffer. The httpd binary uses unsafe string-handling routines such as strcpy or sprintf against attacker-controlled HTTP input, violating safe buffer boundary handling.
Attack Vector
An attacker sends a crafted HTTP POST request to /goform/SetSysTimeCfg with an oversized timeZone value. The request must reach the management interface, which is typically exposed on the LAN but may be remotely reachable when administrators enable WAN management. The exploit has been disclosed publicly through GitHub CVE Documentation and VulDB Entry #317574, increasing the likelihood of opportunistic scanning and exploitation.
No verified proof-of-concept code is included in this article. Refer to the public disclosure for technical reproduction details.
Detection Methods for CVE-2025-8160
Indicators of Compromise
- HTTP POST requests to /goform/SetSysTimeCfg containing abnormally long timeZone parameter values
- Unexpected httpd process crashes or restarts on Tenda AC20 devices
- Outbound connections from the router to unfamiliar IP addresses, indicating possible post-exploitation activity
- Unauthorized changes to router configuration, DNS settings, or firmware
Detection Strategies
- Inspect web traffic to router management interfaces for requests targeting /goform/SetSysTimeCfg with timeZone payloads exceeding expected length
- Deploy network intrusion detection signatures matching oversized parameters in Tenda goform URIs
- Monitor router syslog output (if exported) for httpd segmentation faults or watchdog reboots
Monitoring Recommendations
- Centralize router logs into a SIEM and alert on repeated httpd crashes or reboot events
- Track DNS settings on managed networks and alert on unauthorized resolver changes that may indicate router compromise
- Baseline normal management traffic to AC20 devices and flag requests originating from outside administrative subnets
How to Mitigate CVE-2025-8160
Immediate Actions Required
- Restrict access to the router's web management interface to trusted internal subnets only
- Disable remote WAN management on Tenda AC20 devices until a vendor patch is verified
- Change default and weak administrative credentials, since exploitation requires low-privilege authenticated access
- Audit AC20 deployments and inventory firmware versions matching 16.03.08.12 or earlier
Patch Information
At the time of publication, no vendor advisory or fixed firmware version has been published by Tenda for CVE-2025-8160. Administrators should monitor the Tenda Official Site for firmware updates and consult the VulDB CTI Entry #317574 for tracking remediation status.
Workarounds
- Place AC20 devices behind a separate firewall and block external access to TCP/80 and TCP/443 on the router WAN interface
- Segment management traffic onto a dedicated VLAN accessible only to administrative hosts
- Where feasible, replace end-of-support consumer routers with actively maintained models that receive timely security updates
# Example: block external access to Tenda AC20 management interface using iptables on an upstream gateway
iptables -A FORWARD -p tcp -d <AC20_LAN_IP> --dport 80 -m iprange ! --src-range 10.0.0.0-10.0.0.255 -j DROP
iptables -A FORWARD -p tcp -d <AC20_LAN_IP> --dport 443 -m iprange ! --src-range 10.0.0.0-10.0.0.255 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
