CVE-2026-2550 Overview
A critical unrestricted file upload vulnerability has been discovered in EFM ipTIME A6004MX router firmware version 14.18.2. The vulnerability exists in the commit_vpncli_file_upload function within the /cgi/timepro.cgi file, allowing remote attackers to upload arbitrary files without proper validation or authentication. This vulnerability could enable complete system compromise of affected network devices.
Critical Impact
Remote attackers can exploit this vulnerability to upload malicious files to the router, potentially leading to remote code execution, persistent backdoor installation, or complete device takeover without any user interaction.
Affected Products
- EFM ipTIME A6004MX firmware version 14.18.2
- ipTIME A6004MX routers running vulnerable CGI handler
Discovery Timeline
- 2026-02-16 - CVE-2026-2550 published to NVD
- 2026-02-18 - Last updated in NVD database
Technical Details for CVE-2026-2550
Vulnerability Analysis
This vulnerability represents an unrestricted file upload flaw (CWE-284: Improper Access Control) in the ipTIME A6004MX router's web management interface. The commit_vpncli_file_upload function within /cgi/timepro.cgi fails to implement proper access controls and file validation, allowing unauthenticated remote attackers to upload arbitrary files to the device.
The attack can be performed remotely over the network without requiring any authentication or user interaction. Once exploited, an attacker could upload malicious scripts or firmware components, potentially achieving persistent access to the network device and all traffic passing through it.
The exploit has been publicly disclosed, and the vendor (EFM) was contacted regarding this vulnerability but did not respond. This lack of vendor acknowledgment increases the risk for organizations using affected devices as no official patch timeline has been established.
Root Cause
The root cause of this vulnerability lies in improper access control implementation within the CGI handler. The commit_vpncli_file_upload function does not adequately verify:
- Authentication status of the requesting user
- File type restrictions for uploaded content
- Upload destination path validation
- File content sanitization
This combination of missing security controls allows any remote attacker to directly interact with the file upload functionality without restriction.
Attack Vector
The attack vector for CVE-2026-2550 is network-based, requiring no privileges or user interaction. An attacker can exploit this vulnerability by:
- Identifying an exposed ipTIME A6004MX router on the network or internet
- Crafting a malicious HTTP request targeting the /cgi/timepro.cgi endpoint
- Invoking the commit_vpncli_file_upload function with an arbitrary file payload
- Uploading malicious content such as web shells, backdoors, or modified configuration files
- Executing the uploaded content to gain persistent access to the device
The vulnerability does not require a valid session or any form of authentication, making it trivially exploitable against any accessible device.
Detection Methods for CVE-2026-2550
Indicators of Compromise
- Unusual HTTP POST requests to /cgi/timepro.cgi containing file upload data
- Unexpected files appearing in router file system directories
- Unauthorized configuration changes or new administrative accounts
- Network traffic anomalies originating from the router device
- Log entries showing repeated access to the VPN client upload functionality
Detection Strategies
- Monitor network traffic for HTTP requests targeting /cgi/timepro.cgi with file upload payloads
- Implement IDS/IPS rules to detect exploitation attempts against ipTIME devices
- Review router access logs for unauthenticated requests to administrative endpoints
- Deploy network monitoring to identify communication patterns indicative of compromised IoT devices
Monitoring Recommendations
- Enable comprehensive logging on network perimeter devices for traffic destined to router management interfaces
- Implement file integrity monitoring on router firmware and configuration files where supported
- Monitor for outbound connections from router devices to unknown external hosts
- Establish baseline behavior for router management interface access patterns
How to Mitigate CVE-2026-2550
Immediate Actions Required
- Restrict access to the router's web management interface to trusted internal networks only
- Implement firewall rules blocking external access to ports 80/443 on the affected device
- Monitor for exploitation attempts using network intrusion detection systems
- Consider replacing the affected device with a supported alternative if no patch becomes available
Patch Information
No official patch is currently available from the vendor. According to the disclosure, EFM was contacted about this vulnerability but did not respond. Organizations should monitor for firmware updates from ipTIME and apply them immediately when available. Technical details and discussion can be found in the GitHub Issue Discussion and VulDB advisory.
Workarounds
- Disable remote management access to the router's web interface entirely
- Place the router management interface on an isolated VLAN accessible only to authorized administrators
- Implement a VPN requirement for all remote administrative access to the network
- Deploy a web application firewall in front of the router management interface to filter malicious requests
# Example firewall rules to restrict access to router management interface
# Block external access to router web interface on port 80
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
# Block external access to router web interface on port 443
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP
# Allow only specific admin workstation access
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.100 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
