CVE-2026-1978: NanoCMS RCE Vulnerability

CVE-2026-1978 Overview

A direct request vulnerability has been identified in kalyan02 NanoCMS versions up to 0.4. This security flaw exists in the User Information Handler component, specifically affecting the /data/pagesdata.txt file. The vulnerability allows attackers to bypass intended access restrictions and directly access sensitive data files that should not be publicly accessible.

Critical Impact

Remote attackers can directly access sensitive user information stored in pagesdata.txt without authentication, potentially exposing site configuration and content data.

Affected Products

• kalyan02 NanoCMS up to version 0.4
• NanoCMS installations with default file configurations
• Web servers hosting NanoCMS with accessible /data/ directory

Discovery Timeline

• February 6, 2026 - CVE-2026-1978 published to NVD
• February 6, 2026 - Last updated in NVD database

Technical Details for CVE-2026-1978

Vulnerability Analysis

This vulnerability is classified under CWE-425 (Direct Request or Forced Browsing). NanoCMS stores page data and potentially sensitive configuration information in a flat-file structure within the /data/ directory. The pagesdata.txt file is directly accessible via HTTP requests without any access control mechanisms in place.

The flat-file CMS architecture stores all page content and metadata in text files rather than a database. While this simplifies deployment, it creates significant security risks when these data files are placed within the web root and lack proper access restrictions. An attacker can simply navigate to the file path directly in their browser or use automated tools to enumerate and retrieve the contents.

Root Cause

The root cause of this vulnerability is insufficient access control on sensitive data files within the NanoCMS application. The /data/pagesdata.txt file is stored in a location accessible to web requests, and the application does not implement any mechanism to prevent direct access to this resource. This is a common issue in flat-file CMS systems where proper .htaccess rules or server configuration directives are not implemented to restrict access to data directories.

Attack Vector

The attack can be initiated remotely over the network with no authentication required. An attacker simply needs to know or guess the file path to the sensitive data file. The exploitation process involves:

1. Identifying a target running NanoCMS
2. Sending a direct HTTP GET request to /data/pagesdata.txt
3. Retrieving the contents of the file which may contain page configurations, content data, and potentially sensitive information

The vulnerability requires no user interaction and can be exploited with minimal technical knowledge. The exploit has been publicly disclosed, increasing the likelihood of opportunistic attacks against unpatched installations.

Detection Methods for CVE-2026-1978

Indicators of Compromise

• Unusual HTTP requests targeting /data/pagesdata.txt or similar paths in the /data/ directory
• Access logs showing direct requests to .txt files within application data directories
• Enumeration patterns in web server logs indicating directory traversal or forced browsing attempts

Detection Strategies

• Configure web server access logging to capture all requests to the /data/ directory and set up alerts for direct file access
• Implement Web Application Firewall (WAF) rules to block direct requests to known sensitive file paths
• Use intrusion detection systems (IDS) to identify patterns consistent with forced browsing attacks

Monitoring Recommendations

• Monitor web server access logs for requests containing /data/pagesdata.txt or similar sensitive file paths
• Set up alerting for HTTP 200 responses to requests targeting data directory files
• Review logs regularly for signs of automated scanning or enumeration activity targeting CMS-specific paths

How to Mitigate CVE-2026-1978

Immediate Actions Required

• Move the /data/ directory outside of the web root to prevent direct HTTP access
• Implement .htaccess rules (Apache) or equivalent server configuration to deny access to the /data/ directory
• Review and restrict file permissions on all sensitive data files
• Consider migrating to a more actively maintained CMS solution if security updates are not available

Patch Information

No official patch has been released by the vendor at this time. The NanoCMS project appears to be unmaintained, as the GitHub repository shows no recent activity. Users are advised to implement the workarounds listed below or consider alternative CMS solutions. Additional vulnerability details can be found at VulDB #344500.

Workarounds

• Add server configuration rules to deny direct access to the /data/ directory and all its contents
• Relocate sensitive data files outside the document root directory
• Implement application-level access controls if modifying the CMS code is feasible
• Use a reverse proxy to filter and block requests to sensitive file paths

# Apache .htaccess configuration to protect data directory
# Place this file in the /data/ directory

# Deny all direct access to this directory
<IfModule mod_authz_core.c>
    Require all denied
</IfModule>

# For Apache 2.2 compatibility
<IfModule !mod_authz_core.c>
    Order deny,allow
    Deny from all
</IfModule>