CVE-2025-5607 Overview
CVE-2025-5607 is a buffer overflow vulnerability in the Tenda AC18 wireless router running firmware version 15.03.05.05. The flaw resides in the formSetPPTPUserList function within the /goform/setPptpUserList endpoint. An attacker can manipulate the list argument to overflow a fixed-size buffer in the device's HTTP service. The issue is reachable over the network and the exploit has been publicly disclosed. Successful exploitation can corrupt adjacent memory regions on the router, leading to service disruption or arbitrary code execution on the embedded device.
Critical Impact
Remote attackers with low-level authentication can trigger a buffer overflow in the router's web management interface, compromising confidentiality, integrity, and availability of the affected device.
Affected Products
- Tenda AC18 hardware router
- Tenda AC18 firmware version 15.03.05.05
- Deployments exposing the /goform/setPptpUserList endpoint
Discovery Timeline
- 2025-06-04 - CVE-2025-5607 published to NVD
- 2025-06-17 - Last updated in NVD database
Technical Details for CVE-2025-5607
Vulnerability Analysis
The vulnerability affects the formSetPPTPUserList handler in the Tenda AC18 web management daemon. The function processes the list parameter submitted to /goform/setPptpUserList without enforcing a length check before copying the value into a fixed-size stack buffer. This classic memory-safety failure is categorized under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer) and [CWE-120] (Classic Buffer Overflow). The Tenda AC18 runs on a MIPS-based architecture, and overflowing the stack buffer can overwrite saved return addresses or function pointers used by the embedded web server. Public disclosure increases the risk that working exploits will be weaponized against exposed devices.
Root Cause
The handler reads an attacker-controlled string from the HTTP request body and copies it into a local buffer using an unbounded copy routine. The absence of input length validation on the list argument allows oversized payloads to corrupt adjacent stack memory. This is consistent with prior buffer overflow patterns reported across other formSet* handlers in Tenda firmware.
Attack Vector
Exploitation occurs by sending a crafted HTTP POST request to /goform/setPptpUserList on the router's management interface. The attacker supplies an oversized list parameter to trigger the overflow. Network access to the router's web interface and a valid low-privilege session are required. Routers that expose administration to the WAN side or to untrusted LAN segments are at the highest risk of remote compromise.
No verified proof-of-concept code is available in the referenced sources. See the Notion Security Overview and VulDB #311093 for further technical details on the affected handler.
Detection Methods for CVE-2025-5607
Indicators of Compromise
- HTTP POST requests to /goform/setPptpUserList containing abnormally long list parameter values.
- Repeated router reboots, crash loops, or unexpected restarts of the httpd process.
- Outbound connections from the router to unfamiliar hosts following web interface activity.
- New or modified PPTP user entries that do not correspond to administrator action.
Detection Strategies
- Inspect HTTP traffic destined for the router management interface for requests exceeding expected parameter lengths on /goform/ endpoints.
- Deploy network IDS signatures that match oversized list= payloads on Tenda goform URIs.
- Correlate router syslog entries indicating service crashes with preceding HTTP activity.
Monitoring Recommendations
- Forward router logs to a centralized log platform and alert on httpd restart events.
- Monitor for unauthorized configuration changes to PPTP, VPN, and DNS settings on consumer-grade routers.
- Track scanning activity targeting TCP/80 and TCP/443 on network segments where SOHO devices reside.
How to Mitigate CVE-2025-5607
Immediate Actions Required
- Disable remote WAN-side administration on the Tenda AC18 to prevent internet-based exploitation attempts.
- Restrict access to the router's web management interface to a dedicated administrative VLAN or trusted host.
- Rotate administrator credentials and disable the PPTP service if it is not required.
- Inventory all Tenda AC18 devices running firmware 15.03.05.05 and prioritize them for replacement or update.
Patch Information
At the time of NVD publication, no vendor advisory or patched firmware release for CVE-2025-5607 was listed in the referenced sources. Administrators should monitor the Tenda Official Site for firmware updates addressing the formSetPPTPUserList handler. Where no patch is available, consider replacing affected devices with hardware that receives active security support.
Workarounds
- Place the router behind an upstream firewall and block external access to TCP/80 and TCP/443 on the device.
- Disable the PPTP VPN feature in the router configuration to reduce the attack surface of the vulnerable handler.
- Segment IoT and management traffic so that only authorized hosts can reach the router's administrative interface.
# Example: block external access to the router management interface using an upstream firewall (iptables)
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -j DROP
# Restrict management access to a single admin host on the LAN
iptables -I FORWARD -s <admin_host_ip> -d <router_ip> -p tcp --dport 80 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
