CVE-2019-25487: SAPIDO RB-1732 RCE Vulnerability

CVE-2019-25487 Overview

CVE-2019-25487 is a remote command execution vulnerability in the SAPIDO RB-1732 router running firmware version 2.0.43. The device exposes a formSysCmd endpoint that accepts a sysCmd parameter without authentication or input validation. Unauthenticated attackers can submit POST requests containing arbitrary shell commands and execute them with router-level privileges. Successful exploitation grants control over the device, enabling traffic interception, network pivoting, persistent backdoor installation, and integration into botnets targeting other internet-exposed assets.

Critical Impact
Unauthenticated attackers can execute arbitrary operating system commands on the router with elevated privileges through a single HTTP POST request.

Affected Products

SAPIDO RB-1732 router
Firmware version 2.0.43
Web administration interface exposing the formSysCmd handler

Discovery Timeline

2026-03-11 - CVE-2019-25487 published to the National Vulnerability Database (NVD)
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2019-25487

Vulnerability Analysis

The vulnerability is a command injection flaw in the router's web management interface. The formSysCmd handler reads the sysCmd POST parameter and passes its contents to a system shell without sanitization or escaping. The endpoint does not enforce authentication, so any client with network reachability to the management interface can trigger command execution.

The weakness is tracked under [CWE-639]. Exploitation yields code execution as the user running the router's web service, which on embedded Linux-based routers is typically root. Attackers can read configuration files, extract Wi-Fi credentials, modify DNS settings, and load additional binaries onto the device.

Root Cause

The formSysCmd handler concatenates attacker-controlled input directly into a shell command string before invoking the system shell. There is no allow-list of permitted commands, no input filtering, and no authentication check protecting the endpoint. The handler appears to have been intended as an internal diagnostic interface but is exposed on the router's HTTP service.

Attack Vector

An attacker sends an HTTP POST request to the formSysCmd endpoint on the router's web interface. The request body contains the sysCmd parameter populated with a shell command such as a reverse shell, file download, or configuration dump. The router processes the request, executes the command, and returns the output in the HTTP response. The attack requires network access to the management interface and no user interaction.

Technical details and a proof-of-concept request are documented in the Exploit-DB entry 47031 and the VulnCheck advisory for SAPIDO RB-1732.

Detection Methods for CVE-2019-25487

Indicators of Compromise

HTTP POST requests to /formSysCmd containing a sysCmd parameter from external or unexpected source addresses
Outbound connections from the router to unfamiliar hosts following web requests to the management interface
Unexpected processes such as wget, tftp, nc, or shell interpreters spawned by the router's HTTP daemon
Modifications to router configuration files, DNS settings, or firewall rules outside of administrator activity

Detection Strategies

Inspect HTTP traffic to router management interfaces for POST requests targeting formSysCmd and flag any request containing shell metacharacters in the sysCmd field
Monitor egress traffic from router IP addresses for connections to non-ISP destinations on ports commonly used by reverse shells
Correlate router web access logs with new outbound TCP sessions originating from the device

Monitoring Recommendations

Forward router syslog and web access logs to a central logging platform for retention and analysis
Alert on any administrative HTTP endpoint receiving unauthenticated POST requests from WAN-side addresses
Track firmware version inventory across SOHO devices to identify SAPIDO RB-1732 units running 2.0.43

How to Mitigate CVE-2019-25487

Immediate Actions Required

Restrict access to the router's web management interface to trusted internal addresses only and disable WAN-side administration
Remove SAPIDO RB-1732 devices running firmware 2.0.43 from production networks where vendor patches are unavailable
Replace end-of-life SAPIDO RB-1732 hardware with currently supported routers that receive security updates
Reset device configuration and credentials after isolating any potentially exploited unit

Patch Information

No vendor advisory or patched firmware release is referenced in the available CVE data. Operators should consult the vendor directly and treat affected devices as unpatched until confirmed otherwise. Refer to the VulnCheck advisory for the latest status.

Workarounds

Place the router behind an upstream firewall that blocks inbound HTTP and HTTPS to the management interface
Apply access control lists permitting management connections only from a dedicated administrative subnet
Disable remote management features in the router configuration if they are not required
Segment vulnerable devices onto an isolated VLAN with restricted egress until they can be decommissioned

bash

# Configuration example: block external access to the router management interface
iptables -A INPUT -i wan0 -p tcp --dport 80 -j DROP
iptables -A INPUT -i wan0 -p tcp --dport 443 -j DROP
iptables -A INPUT -p tcp --dport 80 -m string --string "formSysCmd" --algo bm -j DROP