CVE-2025-5436 Overview
CVE-2025-5436 is an information disclosure vulnerability in the Multilaser Sirius RE016 router running firmware version MLT1.0. The flaw resides in unspecified processing logic within the /cgi-bin/cstecgi.cgi endpoint. Remote attackers can trigger the issue over the network without authentication or user interaction to retrieve sensitive information from the device. A public proof-of-concept is available, and the vendor did not respond to disclosure attempts. The weakness is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Critical Impact
Unauthenticated remote attackers can extract sensitive router information through the cstecgi.cgi interface, exposing configuration data that facilitates follow-on attacks against the device and connected network.
Affected Products
- Multilaser Sirius RE016 router
- Firmware version MLT1.0
- CGI handler /cgi-bin/cstecgi.cgi
Discovery Timeline
- 2025-06-02 - CVE-2025-5436 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-5436
Vulnerability Analysis
The vulnerability affects the cstecgi.cgi binary that serves the router's web-based management interface. Unauthenticated requests to this endpoint disclose information that should be restricted to administrative users. The issue is reachable over the network, meaning any attacker with connectivity to the router's management interface can send crafted HTTP requests to trigger the disclosure.
Information disclosure in embedded router CGI handlers commonly exposes configuration parameters, credential material, or network topology data. Attackers use the leaked data to fingerprint the device, pivot into the internal network, or prepare more targeted exploitation.
Root Cause
The root cause is missing authorization enforcement in the request handler for /cgi-bin/cstecgi.cgi. The endpoint returns sensitive data to callers without verifying session or credential state. This aligns with [CWE-200], which covers exposure of sensitive data to actors that should not have access.
Attack Vector
Exploitation requires only network access to the router's HTTP management interface. The attacker sends a crafted request to the vulnerable CGI endpoint and parses the response. No credentials, tokens, or user interaction are required. A public proof-of-concept script is hosted in the GitHub PoC Repository, and additional technical context is tracked in VulDB #310769.
Detection Methods for CVE-2025-5436
Indicators of Compromise
- Unexpected HTTP GET or POST requests to /cgi-bin/cstecgi.cgi from external or unmanaged sources.
- Repeated requests to the router web interface from a single IP address in a short window, consistent with automated probing.
- User-Agent strings referencing Python or scripted HTTP clients targeting the RE016 management interface.
Detection Strategies
- Inspect router and upstream firewall logs for requests to cstecgi.cgi originating outside the trusted management network.
- Deploy network signatures matching the request patterns published in the public proof-of-concept script.
- Correlate management-interface access with authentication events to identify successful data retrieval that lacks a corresponding login.
Monitoring Recommendations
- Restrict router management interfaces to a dedicated VLAN and monitor for any traffic that bypasses that segmentation.
- Alert on outbound connections from the router to unknown hosts, which may indicate post-exploitation activity following data theft.
- Track firmware version and configuration drift on Multilaser Sirius RE016 devices to detect tampering.
How to Mitigate CVE-2025-5436
Immediate Actions Required
- Block external access to the router's web management interface at the perimeter and permit administration only from trusted internal hosts.
- Disable remote (WAN-side) management on the RE016 if it is enabled.
- Rotate any credentials, Wi-Fi keys, and configuration secrets that may have been exposed through the disclosure.
Patch Information
No vendor patch is available. The vendor was contacted about this disclosure but did not respond, according to the VulDB submission. Organizations should track VulDB CTI ID #310769 for updates and consider replacing the device if remediation is unavailable.
Workarounds
- Place the router behind an upstream firewall that blocks inbound access to TCP ports serving the management interface.
- Segment the RE016 from sensitive internal networks to limit the value of any information an attacker can retrieve.
- Replace the affected device with a supported router that receives vendor security updates when perimeter controls cannot be enforced.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
