CVE-2025-11418: Tenda CH22 Buffer Overflow Vulnerability

CVE-2025-11418 Overview

CVE-2025-11418 is a stack-based buffer overflow vulnerability affecting Tenda CH22 routers running firmware versions up to 1.0.0.1. The flaw resides in the formWrlsafeset function handling requests to /goform/AdvSetWrlsafeset within the HTTP request handler component. Attackers can manipulate the mit_ssid_index parameter to corrupt the stack remotely without authentication. The exploit details have been disclosed publicly, increasing the likelihood of opportunistic exploitation against exposed devices. The weakness is categorized under [CWE-119], improper restriction of operations within the bounds of a memory buffer.

Critical Impact
Unauthenticated remote attackers can trigger a stack-based buffer overflow over the network, potentially leading to arbitrary code execution or denial of service on affected Tenda CH22 routers.

Affected Products

Tenda CH22 router (hardware)
Tenda CH22 firmware versions up to and including 1.0.0.1
HTTP request handler component exposing /goform/AdvSetWrlsafeset

Discovery Timeline

2025-10-08 - CVE-2025-11418 published to NVD
2025-10-09 - Last updated in NVD database

Technical Details for CVE-2025-11418

Vulnerability Analysis

The vulnerability lives in the formWrlsafeset function inside the Tenda CH22 web management interface. The function processes HTTP POST requests sent to /goform/AdvSetWrlsafeset, which is used to configure wireless security settings. When the handler reads the mit_ssid_index parameter from the request, it copies the attacker-supplied value into a fixed-size stack buffer without enforcing length boundaries. A sufficiently long input overflows the buffer and overwrites adjacent stack data, including saved return addresses. The attack requires no authentication and no user interaction. Successful exploitation can hijack control flow and execute arbitrary code in the context of the router's web service, which typically runs with elevated privileges.

Root Cause

The root cause is missing input validation on the mit_ssid_index argument before it is copied into a local stack buffer. The firmware relies on unsafe string operations that do not check destination buffer length. This pattern is consistent with [CWE-119] memory corruption issues observed across multiple Tenda product families. Once the saved return address is overwritten, an attacker controlling the overflow content can redirect execution to attacker-supplied code or an existing code path useful for exploitation.

Attack Vector

Exploitation occurs over the network against the router's HTTP management interface. An attacker sends a crafted POST request to /goform/AdvSetWrlsafeset containing an oversized mit_ssid_index value. If the management interface is reachable, including via WAN-side exposure or pivoting from a compromised LAN host, the attack succeeds without credentials. Refer to the GitHub Issue on CVE and VulDB #327354 entries for additional technical context.

Detection Methods for CVE-2025-11418

Indicators of Compromise

HTTP POST requests targeting /goform/AdvSetWrlsafeset with abnormally long mit_ssid_index parameter values.
Unexpected reboots or crashes of the Tenda CH22 web management daemon.
Outbound connections from the router to unfamiliar hosts following inbound requests to the management interface.
Changes to wireless or firewall configuration not initiated by an administrator.

Detection Strategies

Inspect web server and reverse-proxy logs for requests to /goform/AdvSetWrlsafeset that contain parameter values exceeding expected length thresholds.
Deploy network IDS signatures that flag oversized form parameters in HTTP requests to embedded device management paths.
Correlate router-originated traffic anomalies with prior administrative HTTP traffic to detect post-exploitation activity.

Monitoring Recommendations

Forward router and edge firewall logs to a centralized log platform for retention and analysis.
Alert on any WAN-side access attempts to the router's HTTP management interface.
Monitor for repeated POST requests to /goform/ endpoints from a single source within short time windows.

How to Mitigate CVE-2025-11418

Immediate Actions Required

Disable remote (WAN) administration on affected Tenda CH22 devices until a vendor patch is available.
Restrict access to the LAN-side management interface to a dedicated administrative VLAN or trusted host list.
Place affected devices behind a network filter that blocks requests to /goform/AdvSetWrlsafeset from untrusted networks.
Audit existing devices for unauthorized configuration changes and rotate Wi-Fi and administrative credentials.

Patch Information

No vendor advisory or firmware patch has been published in the referenced sources at the time of writing. Check the Tenda Official Website for firmware updates beyond version 1.0.0.1. Until a fixed firmware release is available, treat the device as exposed and rely on network-level controls.

Workarounds

Disable the HTTP management service if remote configuration is not required.
Use access control lists on upstream firewalls to permit management traffic only from specific administrative IP addresses.
Segment affected routers away from sensitive internal networks to limit blast radius if exploitation occurs.
Replace end-of-support or unpatched CH22 units with a currently supported router model.

bash

# Example iptables rule to block external access to the vulnerable endpoint
iptables -A INPUT -p tcp --dport 80 -m string \
  --string "/goform/AdvSetWrlsafeset" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string \
  --string "/goform/AdvSetWrlsafeset" --algo bm -j DROP