CVE-2018-25164: EverSync Information Disclosure Flaw

CVE-2018-25164 Overview

CVE-2018-25164 is an arbitrary file download vulnerability affecting EverSync version 0.5. This vulnerability allows unauthenticated attackers to access sensitive files by requesting them directly from the files directory. Attackers can send GET requests to the files directory to download database files like db.sq3 containing application data and credentials.

Critical Impact

Unauthenticated attackers can remotely download sensitive database files containing credentials and application data without any authentication requirements.

Affected Products

• EverSync 0.5

Discovery Timeline

• 2026-03-06 - CVE-2018-25164 published to NVD
• 2026-03-09 - Last updated in NVD database

Technical Details for CVE-2018-25164

Vulnerability Analysis

This vulnerability is classified under CWE-552 (Files or Directories Accessible to External Parties), representing a critical access control failure in the EverSync application. The core issue stems from improper access restrictions on the files directory, which exposes sensitive application files to unauthenticated network requests.

The vulnerability enables remote attackers to bypass authentication entirely and directly access the server's file system through the exposed files directory. The attack requires no user interaction and can be executed from any network-accessible position, making it particularly dangerous for internet-facing deployments.

Once exploited, attackers gain access to sensitive data stores including the SQLite database file (db.sq3), which typically contains user credentials, application configuration data, and other sensitive information. This exposure can lead to complete compromise of user accounts and potentially enable further attacks against connected systems.

Root Cause

The root cause is improper access control implementation in EverSync 0.5. The application fails to enforce authentication or authorization checks when serving files from the files directory. This design flaw allows any external party to directly request and download files that should be protected, violating the principle of least privilege and secure-by-default configurations.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker simply needs to send HTTP GET requests to the files directory path on the vulnerable EverSync server. By targeting known file names such as db.sq3, attackers can systematically download sensitive application data.

The exploitation is straightforward: an attacker identifies a vulnerable EverSync 0.5 instance, constructs GET requests targeting the files directory, and retrieves database files containing credentials and configuration data. Technical details and proof-of-concept information are available in the Exploit-DB #45868 entry and the VulnCheck Advisory on Eversync.

Detection Methods for CVE-2018-25164

Indicators of Compromise

• HTTP GET requests targeting the /files/ directory path, particularly for database files like db.sq3
• Unusual volume of file download requests from external IP addresses
• Access logs showing successful retrieval of sensitive file types from the files directory
• Unexpected outbound data transfers following successful file access attempts

Detection Strategies

• Configure web server logging to capture all requests to the files directory and alert on access from unauthenticated sessions
• Implement network intrusion detection rules to identify requests containing patterns associated with database file downloads (.sq3, .db, .sqlite)
• Deploy file integrity monitoring on sensitive directories to detect unauthorized access attempts
• Monitor for reconnaissance activity targeting known EverSync directory structures

Monitoring Recommendations

• Enable verbose access logging for all file serving endpoints in EverSync deployments
• Set up real-time alerting for any external requests to the files directory
• Implement network traffic analysis to detect potential data exfiltration following file download attempts
• Review authentication logs for anomalies that may indicate exploitation attempts

How to Mitigate CVE-2018-25164

Immediate Actions Required

• Restrict network access to EverSync instances using firewall rules or network segmentation
• Disable public access to the files directory immediately if possible
• Audit access logs for evidence of exploitation and identify any compromised credentials
• Consider taking vulnerable EverSync instances offline until mitigation measures are implemented

Patch Information

No vendor patch information is currently available in the CVE data. Organizations should monitor the VulnCheck Advisory on Eversync for updates regarding official fixes. Consider upgrading to a newer version of EverSync if available, or migrating to an alternative synchronization solution.

Workarounds

• Implement web server access controls (such as .htaccess rules or nginx location blocks) to deny external access to the files directory
• Deploy a reverse proxy with authentication requirements in front of EverSync
• Move sensitive database files outside the web-accessible directory structure
• Implement network-level access controls to restrict EverSync access to trusted IP ranges only

# Example nginx configuration to block access to files directory
location /files/ {
    deny all;
    return 403;
}

# Alternative: Restrict to localhost only
location /files/ {
    allow 127.0.0.1;
    deny all;
}