CVE-2025-26211: Gibbonedu Gibbon CSRF Vulnerability

CVE-2025-26211 Overview

CVE-2025-26211 is a Cross-Site Request Forgery (CSRF) vulnerability affecting Gibbon, an open-source school management platform developed by GibbonEdu. The vulnerability exists in versions prior to 29.0.00 and allows attackers to trick authenticated users into performing unintended actions on the application without their consent.

Critical Impact

This CSRF vulnerability enables attackers to perform unauthorized actions on behalf of authenticated users, potentially leading to data manipulation, unauthorized deletions, or privilege escalation within the school management system.

Affected Products

• GibbonEdu Gibbon versions prior to 29.0.00
• Gibbon Timetable Admin module (tt_delete.php)
• All Gibbon deployments without CSRF token validation

Discovery Timeline

• 2025-05-27 - CVE-2025-26211 published to NVD
• 2025-07-18 - Last updated in NVD database

Technical Details for CVE-2025-26211

Vulnerability Analysis

This vulnerability is classified under CWE-352 (Cross-Site Request Forgery). The flaw resides in the application's failure to properly validate the origin of state-changing requests. When a user with administrative privileges is authenticated to Gibbon, an attacker can craft a malicious webpage containing forged requests that execute administrative actions when the victim visits the attacker-controlled page.

The vulnerability specifically affects the Timetable Admin module, where deletion operations can be triggered without proper CSRF token validation. This means that actions like deleting timetable entries, modifying schedules, or altering administrative data could be performed without the user's explicit authorization.

Root Cause

The root cause of this vulnerability is the absence of anti-CSRF token validation in the tt_delete.php file within the Timetable Admin module. The application processes state-changing requests based solely on session cookies without verifying that the request originated from a legitimate form submission within the application. This architectural oversight allows attackers to forge requests that appear to come from authenticated users.

Attack Vector

The attack is network-based and requires user interaction. An attacker must craft a malicious webpage, email, or other content containing a forged HTTP request targeting the vulnerable Gibbon endpoint. When an authenticated Gibbon user (typically a school administrator or staff member) interacts with the malicious content, their browser automatically includes session credentials, causing the forged request to be processed as legitimate.

The attack could be delivered through phishing emails sent to school staff, malicious links embedded in documents, or compromised websites that school personnel might visit. Given that Gibbon is used in educational environments, social engineering attacks targeting administrative staff could be particularly effective.

Detection Methods for CVE-2025-26211

Indicators of Compromise

• Unexpected timetable or schedule deletions without corresponding user activity in application logs
• Unusual modification patterns in administrative data coinciding with user browsing external websites
• Log entries showing state-changing operations originating from referrers outside the Gibbon application domain
• Reports from users of actions they did not authorize or remember performing

Detection Strategies

• Monitor HTTP request logs for state-changing operations (POST, DELETE) with external or missing Referer headers
• Implement Web Application Firewall (WAF) rules to detect potential CSRF patterns targeting Gibbon endpoints
• Review application access logs for unusual timing patterns where administrative actions occur immediately after external site visits
• Deploy network-level monitoring to identify requests to sensitive Gibbon endpoints without proper anti-CSRF tokens

Monitoring Recommendations

• Configure alerting for administrative actions performed outside of normal business hours or from unusual IP addresses
• Enable detailed logging for all Timetable Admin module operations, including source IP and referrer information
• Implement user behavior analytics to detect anomalous patterns in administrative actions
• Review audit trails regularly for unauthorized modifications to school data

How to Mitigate CVE-2025-26211

Immediate Actions Required

• Upgrade Gibbon to version 29.0.00 or later immediately to address this CSRF vulnerability
• Review recent administrative actions for any unauthorized changes that may indicate exploitation
• Implement additional network-level protections such as WAF rules to block suspicious cross-origin requests
• Educate administrative staff about phishing risks and the importance of not clicking unknown links while logged into Gibbon

Patch Information

GibbonEdu has released version 29.0.00 which addresses this CSRF vulnerability. The patch introduces proper CSRF token validation for state-changing operations within the application. Administrators should update to this version as soon as possible by following the official upgrade procedures documented in the GitHub Release Notes v29.0.00.

Workarounds

• If immediate patching is not possible, restrict access to Gibbon administrative interfaces to trusted IP ranges only
• Implement strict Content Security Policy headers to reduce the risk of cross-origin request exploitation
• Consider placing Gibbon behind a reverse proxy with CSRF protection capabilities
• Instruct users to log out of Gibbon before browsing other websites and to use separate browser sessions for administrative tasks

# Example: Restrict access to Gibbon admin modules via Apache
<Location "/modules/Timetable Admin/">
    Order deny,allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from 10.0.0.0/8
</Location>