CVE-2025-9812 Overview
CVE-2025-9812 is a buffer overflow vulnerability in the Tenda CH22 router running firmware version 1.0.0.1. The flaw resides in the formexeCommand function within the /goform/exeCommand endpoint. Attackers can trigger the overflow by manipulating the cmdinput argument, leading to memory corruption on the affected device. The vulnerability is exploitable over the network and has been publicly disclosed, increasing the likelihood of opportunistic attacks against exposed routers. The weakness is classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Critical Impact
Remote attackers with low-privileged access can corrupt memory in the Tenda CH22 router web interface, potentially achieving arbitrary code execution and full device compromise.
Affected Products
- Tenda CH22 router (hardware)
- Tenda CH22 firmware version 1.0.0.1
- Web management interface endpoint /goform/exeCommand
Discovery Timeline
- 2025-09-02 - CVE-2025-9812 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-9812
Vulnerability Analysis
The vulnerability exists in the formexeCommand handler exposed through the /goform/exeCommand URI of the Tenda CH22 web management interface. The handler accepts a user-supplied cmdinput parameter and processes it without enforcing proper length validation. When the supplied input exceeds the allocated buffer, adjacent memory is overwritten, corrupting program state on the embedded device.
Because the affected router runs on a constrained embedded Linux platform, successful exploitation can disrupt the HTTP daemon, crash the device, or in some scenarios redirect execution flow. Attackers reaching this endpoint can perform the attack remotely once they have authenticated session access to the web interface.
Root Cause
The root cause is improper bounds checking on the cmdinput argument inside formexeCommand. The function copies attacker-controlled data into a fixed-size buffer without validating input length, satisfying the conditions described by [CWE-119]. Embedded web stacks in consumer routers commonly rely on unsafe string operations such as strcpy or sprintf, which makes overflows of this nature recurrent in Tenda firmware.
Attack Vector
Exploitation requires network reachability to the router's management interface and low-privileged credentials. An attacker submits a crafted HTTP request to /goform/exeCommand containing an oversized cmdinput parameter. The malformed input triggers the overflow inside formexeCommand, allowing memory corruption that can lead to denial of service or arbitrary code execution within the context of the web service.
No verified exploit code is published in a structured PoC repository, but the issue has been publicly disclosed through the GitHub CVE Issue Tracker and indexed in VulDB entry #322139.
Detection Methods for CVE-2025-9812
Indicators of Compromise
- Inbound HTTP POST requests to /goform/exeCommand containing abnormally long cmdinput parameter values
- Unexpected restarts or crashes of the router's web management daemon (httpd)
- Loss of management connectivity following requests to the formexeCommand endpoint
- Outbound connections initiated by the router to unfamiliar IP addresses after web interface access
Detection Strategies
- Inspect web server access logs on the router and upstream proxies for requests to /goform/exeCommand with payloads exceeding typical command length
- Deploy network IDS signatures that flag oversized POST bodies targeting Tenda goform endpoints
- Correlate router availability metrics with HTTP request patterns to identify exploitation attempts that trigger device reboots
Monitoring Recommendations
- Restrict and log access to router management interfaces from corporate or guest networks
- Forward router syslog data to a centralized SIEM for anomaly detection on the management plane
- Alert on any external (WAN-side) access attempts to /goform/ URIs on consumer-grade routers
How to Mitigate CVE-2025-9812
Immediate Actions Required
- Disable remote (WAN) administration on Tenda CH22 devices to eliminate internet-facing exposure of /goform/exeCommand
- Restrict LAN-side access to the web management interface using firewall rules or VLAN segmentation
- Rotate router administrative credentials and enforce strong passwords to limit the attacker's ability to satisfy the low-privilege precondition
- Audit deployed inventory for Tenda CH22 routers running firmware 1.0.0.1
Patch Information
At the time of publication, no vendor advisory or patched firmware release has been published for CVE-2025-9812. Refer to the Tenda Official Website for firmware updates and monitor the VulDB CTI entry for vendor response status. Organizations should plan replacement with a supported model if no patch becomes available.
Workarounds
- Place affected routers behind a network firewall that blocks untrusted access to TCP ports 80 and 443 on the device
- Disable the router's web management interface entirely where command-line or alternative management is available
- Segment IoT and consumer-grade networking equipment away from sensitive corporate assets to limit blast radius if the device is compromised
- Consider replacing end-of-support consumer routers with enterprise-grade equipment that receives timely security updates
# Example: block external access to the router's management interface at an upstream firewall
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -i <wan_iface> -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -i <wan_iface> -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
