CVE-2026-27202: GetSimple CMS Information Disclosure Flaw

CVE-2026-27202 Overview

GetSimple CMS is an open-source content management system designed for simplicity and ease of use. A path traversal vulnerability exists in the Uploaded Files feature of GetSimple CMS that allows attackers to read arbitrary files from the server. This flaw affects all versions of GetSimple CMS and has not been patched at the time of publication, making it a zero-day vulnerability that organizations should address immediately.

Critical Impact

Unauthenticated attackers can exploit the Uploaded Files feature to read sensitive system files, configuration data, and potentially credentials stored on affected web servers running GetSimple CMS.

Affected Products

• GetSimple CMS Community Edition version 3.3.22
• GetSimple CMS all versions (no patch available)

Discovery Timeline

• 2026-02-21 - CVE CVE-2026-27202 published to NVD
• 2026-02-24 - Last updated in NVD database

Technical Details for CVE-2026-27202

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Path Traversal), a type of input validation flaw that allows attackers to access files and directories stored outside the intended directory structure. The vulnerability exists within the Uploaded Files feature of GetSimple CMS, where user-supplied input is not properly sanitized before being used in file system operations.

The attack can be executed remotely over the network without requiring authentication or user interaction. An attacker exploiting this vulnerability gains the ability to read arbitrary files on the target system, potentially exposing sensitive configuration files, database credentials, and other confidential data. While file read operations do not directly allow code execution, the disclosed information could enable further attacks against the system.

Root Cause

The root cause of this vulnerability is improper input validation in the Uploaded Files functionality. The application fails to adequately sanitize file path parameters, allowing directory traversal sequences (such as ../) to escape the intended upload directory and access files elsewhere on the filesystem. This represents a fundamental failure to implement proper input validation and path canonicalization before processing file requests.

Attack Vector

The attack is network-based and requires no authentication or privileges to exploit. An attacker can craft malicious requests to the Uploaded Files feature containing directory traversal sequences to navigate outside the web root and read arbitrary files. Common targets include:

• /etc/passwd on Linux systems
• Application configuration files containing database credentials
• Source code files that may reveal additional vulnerabilities
• Session files or authentication tokens

Due to the lack of an available patch, the vulnerability is exploitable on all current installations of GetSimple CMS. Detailed exploitation methodology can be found in the GitHub Security Advisory published by the maintainers.

Detection Methods for CVE-2026-27202

Indicators of Compromise

• Web server access logs containing path traversal sequences (../, ..%2f, ..%5c) targeting the Uploaded Files feature
• Requests attempting to access sensitive system files such as /etc/passwd, /etc/shadow, or application configuration files
• Unusual file access patterns originating from the CMS application process
• Failed or successful attempts to read files outside the web application directory

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block path traversal sequences in HTTP requests
• Configure intrusion detection systems (IDS) to alert on directory traversal patterns targeting GetSimple CMS endpoints
• Enable verbose logging on web servers and monitor for suspicious file access attempts
• Deploy file integrity monitoring on sensitive configuration files to detect unauthorized access

Monitoring Recommendations

• Review web server access logs regularly for requests containing encoded traversal sequences
• Monitor application error logs for file access permission denied errors that may indicate exploitation attempts
• Set up real-time alerting for access attempts to sensitive directories from the CMS process
• Implement network traffic analysis to identify anomalous request patterns targeting the CMS

How to Mitigate CVE-2026-27202

Immediate Actions Required

• Restrict network access to GetSimple CMS administrative interfaces to trusted IP addresses only
• Implement a Web Application Firewall (WAF) with rules to block path traversal attacks
• Consider temporarily disabling or restricting access to the Uploaded Files feature until a patch is available
• Review and restrict file system permissions to limit the impact of potential file read operations
• Monitor the GetSimple CMS Security Advisories for patch availability

Patch Information

At the time of publication, no official patch is available for this vulnerability. Organizations running GetSimple CMS should implement the workarounds listed below and monitor the vendor's GitHub repository for security updates. Consider migrating to an alternative CMS if the risk is unacceptable for your environment.

Workarounds

• Configure web server rules (Apache .htaccess or Nginx location blocks) to reject requests containing directory traversal patterns
• Implement strict input validation at the web server level using ModSecurity or similar WAF
• Run the CMS application with minimal file system permissions using a restricted user account
• Isolate the CMS deployment in a container or virtual machine to limit the impact of file disclosure
• Consider taking the application offline or restricting access to internal users only until a fix is released

# Example ModSecurity rule to block path traversal attempts
SecRule REQUEST_URI|REQUEST_BODY "@rx \.\.[\\/]" \
    "id:100001,\
    phase:2,\
    deny,\
    status:403,\
    log,\
    msg:'Path Traversal Attempt Detected - CVE-2026-27202',\
    severity:'CRITICAL'"