CVE-2021-47830: GetSimple CMS My SMTP Plugin CSRF Flaw

CVE-2021-47830 Overview

CVE-2021-47830 is a Cross-Site Request Forgery (CSRF) vulnerability affecting the My SMTP Contact Plugin version 1.1.1 for GetSimple CMS. This vulnerability allows attackers to craft malicious webpages that, when visited by an authenticated administrator, can change SMTP configuration settings in the plugin without authorization. While this flaw does not directly enable remote code execution, it poses significant risks by allowing unauthorized modification of email server settings.

Critical Impact

Attackers can manipulate SMTP settings through CSRF attacks, potentially redirecting email communications through attacker-controlled servers, enabling phishing campaigns, or disrupting email functionality for the affected CMS installation.

Affected Products

• GetSimple CMS My SMTP Contact Plugin version 1.1.1
• GetSimple CMS installations using the vulnerable plugin version

Discovery Timeline

• 2026-01-21 - CVE CVE-2021-47830 published to NVD
• 2026-01-21 - Last updated in NVD database

Technical Details for CVE-2021-47830

Vulnerability Analysis

This vulnerability stems from the absence of proper CSRF protection mechanisms in the My SMTP Contact Plugin for GetSimple CMS. The plugin fails to implement anti-CSRF tokens or other request validation methods when processing SMTP configuration changes. This allows an attacker to forge requests that appear to originate from a legitimate administrator session.

The attack requires social engineering to lure an authenticated administrator to visit a malicious webpage. Once the admin visits the page, hidden form submissions or JavaScript-based requests automatically execute configuration changes to the SMTP settings without the administrator's knowledge or consent.

The vulnerability is classified under CWE-352 (Cross-Site Request Forgery), which describes weaknesses where web applications fail to sufficiently verify that requests were intentionally submitted by the user who initiated them.

Root Cause

The root cause of this vulnerability is the lack of CSRF token validation in the plugin's SMTP configuration handling routines. The plugin accepts and processes configuration change requests without verifying that the request originated from a legitimate source or includes a valid session-bound token. This design flaw allows any authenticated session to be hijacked for unauthorized configuration modifications through forged cross-site requests.

Attack Vector

The attack is network-based and requires user interaction to succeed. An attacker would typically:

1. Create a malicious webpage containing hidden form elements or JavaScript code designed to submit requests to the target GetSimple CMS installation
2. Populate the form with the desired SMTP configuration values (such as an attacker-controlled mail server)
3. Distribute the malicious link to target administrators through phishing emails, social media, or compromised websites
4. When an authenticated administrator visits the malicious page, the browser automatically submits the forged request using the admin's session cookies
5. The plugin processes the request and modifies the SMTP configuration without any CSRF validation

The malicious form would target the plugin's configuration endpoint and include fields for SMTP server address, port, authentication credentials, and other email settings. Upon successful exploitation, all outgoing emails from the CMS could be routed through an attacker-controlled server.

Detection Methods for CVE-2021-47830

Indicators of Compromise

• Unexpected changes to SMTP configuration settings in the GetSimple CMS admin panel
• Administrator access logs showing configuration changes without corresponding legitimate admin activity
• Outgoing emails being sent through unfamiliar or unauthorized SMTP servers
• Reports of emails from the CMS being flagged as suspicious or originating from unusual IP addresses

Detection Strategies

• Monitor web server access logs for POST requests to the SMTP configuration endpoint from external referrers
• Implement Content Security Policy (CSP) headers to detect and block unauthorized cross-origin requests
• Review SMTP configuration settings regularly for unauthorized modifications
• Deploy web application firewalls (WAF) configured to detect CSRF attack patterns

Monitoring Recommendations

• Enable detailed logging for all administrative actions within GetSimple CMS
• Set up alerts for any changes to email/SMTP configuration settings
• Monitor network traffic for connections to unexpected external SMTP servers
• Implement email gateway monitoring to detect unusual outbound email patterns

How to Mitigate CVE-2021-47830

Immediate Actions Required

• Verify current SMTP configuration settings and document legitimate values
• Consider temporarily disabling the My SMTP Contact Plugin until a patched version is available
• Implement additional authentication requirements for accessing SMTP configuration pages
• Ensure administrators are trained to avoid clicking suspicious links while logged into the CMS

Patch Information

No official patch information is currently available from the vendor. Organizations should monitor the GetSimple CMS Homepage and the GitHub GetSimpleCMS Repository for security updates. Additional technical details are available through Exploit-DB #49774, Exploit-DB #49798, and the VulnCheck Advisory for GetSimple CMS.

Workarounds

• Add custom CSRF token validation to the plugin's configuration handling code if technically feasible
• Restrict access to the GetSimple CMS admin panel to trusted IP addresses only
• Implement HTTP SameSite cookie attributes to prevent cross-site cookie transmission
• Use a dedicated browser profile for CMS administration to isolate session cookies from regular browsing

# Example Apache configuration to restrict admin access by IP
<Directory "/path/to/getsimple/admin">
    Order deny,allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from 10.0.0.0/8
</Directory>