CVE-2025-13288 Overview
CVE-2025-13288 is a buffer overflow vulnerability in the Tenda CH22 router running firmware version 1.0.0.1. The flaw resides in the fromPptpUserSetting function handling requests to the /goform/PPTPUserSetting endpoint. Attackers can trigger the overflow by manipulating the delno argument over the network. The exploit details have been disclosed publicly, increasing the risk of opportunistic attacks against exposed devices. The vulnerability is tracked under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer) and affects internet-facing router management interfaces.
Critical Impact
Remote authenticated attackers can corrupt memory on the Tenda CH22 router, potentially achieving arbitrary code execution and full device compromise.
Affected Products
- Tenda CH22 hardware device
- Tenda CH22 firmware version 1.0.0.1
- Deployments exposing the /goform/PPTPUserSetting endpoint
Discovery Timeline
- 2025-11-17 - CVE-2025-13288 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-13288
Vulnerability Analysis
The vulnerability exists in the fromPptpUserSetting function exposed through the /goform/PPTPUserSetting web management endpoint. The function processes user-supplied input from the delno parameter without enforcing proper bounds checking. When an attacker supplies an oversized or malformed delno value, the data overruns the destination buffer in memory. This corrupts adjacent stack or heap structures and can lead to control-flow hijacking. The Tenda CH22 is a small office and home office router, so successful exploitation provides a foothold inside the perimeter of affected networks.
Root Cause
The root cause is improper restriction of operations within the bounds of a memory buffer [CWE-119]. The fromPptpUserSetting handler copies the attacker-controlled delno argument into a fixed-size buffer without validating its length. Embedded router firmware frequently uses unsafe C string functions such as strcpy or sprintf in goform handlers, and this pattern is consistent with prior Tenda buffer overflow disclosures.
Attack Vector
The attack is delivered over the network against the router's HTTP management interface. An attacker with low privileges sends a crafted POST request to /goform/PPTPUserSetting containing an overlong delno value. No user interaction is required. Where the management interface is exposed to the WAN, exploitation can be performed remotely from the internet. On internal networks, any host able to reach the management port can attempt exploitation.
No verified public exploit code is available, so the vulnerability is described in prose only. Refer to the GitHub CVE Issue Tracking and VulDB #332628 entries for additional technical context.
Detection Methods for CVE-2025-13288
Indicators of Compromise
- HTTP POST requests to /goform/PPTPUserSetting containing unusually long delno parameter values
- Unexpected reboots, crashes, or watchdog resets on Tenda CH22 devices following inbound HTTP traffic
- Outbound connections from the router to unfamiliar IP addresses or command-and-control infrastructure
- New or modified PPTP user entries that do not match administrative activity
Detection Strategies
- Inspect network traffic for requests targeting /goform/PPTPUserSetting with delno argument lengths exceeding expected boundaries
- Deploy intrusion detection signatures that flag oversized parameters sent to Tenda goform handlers
- Correlate router crash logs with preceding HTTP requests to identify potential exploitation attempts
Monitoring Recommendations
- Forward router syslog and HTTP access logs to a centralized SIEM for pattern analysis
- Alert on any external source attempting to reach the router management interface over WAN
- Track authentication events on the router admin panel to detect credential abuse preceding exploitation
How to Mitigate CVE-2025-13288
Immediate Actions Required
- Restrict access to the router's web management interface to trusted internal hosts only and disable WAN-side administration
- Change default and weak administrative credentials, since exploitation requires low-privileged authentication
- Disable PPTP-related functionality if it is not required in the deployment
- Segment vulnerable Tenda CH22 devices from sensitive network zones until a fix is available
Patch Information
At the time of NVD publication on 2025-11-17, no official vendor patch has been listed for the Tenda CH22 running firmware 1.0.0.1. Check the Tenda Official Website for firmware updates and security advisories. Replace the device with a supported model if the vendor does not release a fix.
Workarounds
- Block external access to TCP ports used by the router management interface at the upstream firewall
- Place the router behind a network access control list that permits administration only from a dedicated management VLAN
- Monitor for and drop HTTP requests containing oversized delno parameters using an inline web application firewall or IPS
- Replace affected hardware with vendor-supported routers that receive timely security updates
# Example firewall rule to restrict router admin access to a management subnet
iptables -A INPUT -p tcp --dport 80 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.0.2.0/24 -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.
