CVE-2025-12322: Tenda CH22 Buffer Overflow Vulnerability

CVE-2025-12322 Overview

CVE-2025-12322 is a buffer overflow vulnerability in the Tenda CH22 router running firmware version 1.0.0.1. The flaw resides in the fromNatStaticSetting function handling requests to /goform/NatStaticSetting. Attackers can manipulate the page argument to overflow a fixed-size buffer in the router's web management interface. The vulnerability is remotely exploitable across the network. Public disclosure includes proof-of-concept details published through VulDB and GitHub, increasing the likelihood of opportunistic exploitation against exposed devices.

Critical Impact
Remote attackers can trigger a buffer overflow in the Tenda CH22 web interface, potentially leading to arbitrary code execution or denial of service on affected routers.

Affected Products

Tenda CH22 router (hardware)
Tenda CH22 firmware version 1.0.0.1
Devices exposing the /goform/NatStaticSetting endpoint

Discovery Timeline

2025-10-27 - CVE-2025-12322 published to NVD
2026-02-24 - Last updated in NVD database

Technical Details for CVE-2025-12322

Vulnerability Analysis

The vulnerability exists in the fromNatStaticSetting function, which processes NAT static mapping configuration submitted to the /goform/NatStaticSetting HTTP endpoint. The function copies the user-supplied page parameter into a fixed-size stack buffer without enforcing proper length validation. This classic memory safety failure maps to [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer) and [CWE-120] (Buffer Copy without Checking Size of Input).

Successful exploitation can corrupt adjacent stack memory, including saved return addresses. On embedded MIPS or ARM targets typical of Tenda devices, this can yield arbitrary code execution as the web server process, which generally runs with elevated privileges. At minimum, the overflow crashes the HTTP daemon and disrupts router availability.

Root Cause

The root cause is unbounded copying of attacker-controlled input from the page HTTP parameter into a fixed-size buffer. The handler trusts client-supplied length information rather than validating against the destination buffer size. No stack canaries or hardened string functions mitigate the copy.

Attack Vector

Exploitation requires network reachability to the router's web management interface and low-privilege authentication on the device. An attacker submits a crafted POST request to /goform/NatStaticSetting with an oversized page argument. Devices with management interfaces exposed to the WAN are at elevated risk. See the public proof-of-concept on GitHub and the VulDB entry #330101 for technical details.

Detection Methods for CVE-2025-12322

Indicators of Compromise

HTTP POST requests to /goform/NatStaticSetting containing an oversized or anomalous page parameter.
Unexpected reboots, web interface crashes, or httpd process restarts on Tenda CH22 devices.
Outbound connections from the router to unknown hosts following suspicious management traffic.

Detection Strategies

Inspect web server access logs on the router for requests to /goform/NatStaticSetting with overly long query parameters.
Deploy network intrusion detection signatures targeting POST bodies to /goform/NatStaticSetting exceeding expected parameter lengths.
Monitor for repeated authentication attempts followed by malformed requests to the router's management interface.

Monitoring Recommendations

Forward router syslog and HTTP traffic metadata to a centralized analytics platform for anomaly review.
Alert on management interface access originating from non-administrative subnets or external IPs.
Baseline normal management traffic patterns and flag deviations in parameter size or request frequency.

How to Mitigate CVE-2025-12322

Immediate Actions Required

Restrict access to the router's web administration interface to trusted internal management hosts only.
Disable remote WAN-side management on Tenda CH22 devices until a vendor fix is applied.
Rotate administrative credentials on the router to limit the value of any captured authentication material.
Audit network perimeter for any Tenda CH22 devices reachable from the internet.

Patch Information

At the time of publication, no vendor patch has been referenced in the NVD entry for CVE-2025-12322. Monitor the Tenda security portal for firmware updates addressing the fromNatStaticSetting buffer overflow. Apply firmware updates promptly when released.

Workarounds

Place affected routers behind a segmented management VLAN with strict ACLs to limit reachability of /goform/NatStaticSetting.
Block inbound traffic to the router's HTTP and HTTPS management ports from untrusted networks at the upstream firewall.
Replace end-of-support Tenda CH22 hardware with a currently maintained device if no firmware fix becomes available.

bash

# Example firewall rule restricting router management access to trusted subnet
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP