CVE-2026-30881: Chamilo LMS SQL Injection Vulnerability

CVE-2026-30881 Overview

CVE-2026-30881 is a SQL Injection vulnerability affecting Chamilo LMS, a widely-used open-source learning management system. The vulnerability exists in the statistics AJAX endpoint where the date_start and date_end parameters from $_REQUEST are embedded directly into a raw SQL string without proper sanitization. Although Database::escape_string() is called downstream, its output is immediately neutralized by str_replace("\'", "'", ...), which restores any injected single quotes—effectively bypassing the escaping mechanism entirely. This allows an authenticated attacker to inject arbitrary SQL statements into the database query, enabling blind time-based and conditional data extraction.

Critical Impact

Authenticated attackers can extract sensitive data from the database through blind SQL injection techniques, potentially compromising user credentials, course content, and other confidential information stored in the LMS.

Affected Products

• Chamilo LMS version 1.11.34 and prior

Discovery Timeline

• 2026-03-16 - CVE-2026-30881 published to NVD
• 2026-03-17 - Last updated in NVD database

Technical Details for CVE-2026-30881

Vulnerability Analysis

This SQL Injection vulnerability (CWE-89) stems from a flawed escaping mechanism in the Chamilo LMS statistics AJAX endpoint. The application attempts to sanitize user input using Database::escape_string(), which would typically prevent SQL injection by escaping single quotes. However, the escaped output is subsequently processed by str_replace("\'", "'", ...), which reverses the escaping by converting escaped single quotes back to their unescaped form.

This implementation error creates a security gap where an attacker with valid authentication can craft malicious date parameters containing SQL injection payloads. The vulnerability enables blind time-based SQL injection, where attackers can infer database information based on response timing, as well as conditional data extraction techniques to systematically retrieve sensitive data.

Root Cause

The root cause is a logic flaw in the input sanitization process. While the developers implemented escaping via Database::escape_string(), the subsequent str_replace() operation that strips backslashes from escaped quotes completely negates the protection. This represents a misunderstanding of secure coding practices, where multiple string manipulation operations inadvertently undo security controls. The date_start and date_end parameters are particularly vulnerable as they flow directly from $_REQUEST into the SQL query construction.

Attack Vector

The attack vector is network-based, requiring only low-privileged authenticated access to the Chamilo LMS platform. An attacker can exploit this vulnerability by:

1. Authenticating to the Chamilo LMS platform with any valid user account
2. Sending crafted HTTP requests to the statistics AJAX endpoint
3. Injecting SQL payloads within the date_start or date_end parameters
4. Using time-based blind SQL injection techniques (e.g., SLEEP() functions) to infer query results
5. Systematically extracting database contents through conditional response analysis

The vulnerability does not require user interaction and can be exploited remotely over the network. The statistics AJAX endpoint processes the malicious input, allowing attackers to manipulate database queries and extract sensitive information including user credentials, personal data, and course materials.

Detection Methods for CVE-2026-30881

Indicators of Compromise

• Unusual or excessive requests to the statistics AJAX endpoint with malformed date parameters
• Database query logs showing SQL syntax errors or time-based injection patterns (e.g., SLEEP(), BENCHMARK())
• Abnormally long response times from the statistics endpoint indicating time-based injection attempts
• Web server logs containing encoded SQL injection payloads in date_start or date_end parameters

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect SQL injection patterns in date parameter fields
• Monitor application logs for repeated failed requests or error messages from the statistics endpoint
• Implement database activity monitoring to detect unusual query patterns or data extraction attempts
• Review access logs for authenticated users making excessive requests to the vulnerable endpoint

Monitoring Recommendations

• Enable detailed logging on the Chamilo LMS statistics module to capture all parameter values
• Configure alerts for SQL injection signatures in HTTP request parameters
• Monitor database performance for unusual spikes in query execution time that may indicate time-based attacks
• Implement rate limiting on AJAX endpoints to slow down automated exploitation attempts

How to Mitigate CVE-2026-30881

Immediate Actions Required

• Upgrade Chamilo LMS to version 1.11.36 or later immediately
• If immediate upgrade is not possible, disable or restrict access to the statistics AJAX endpoint
• Review database logs for evidence of exploitation and assess potential data compromise
• Audit user accounts for any unauthorized access or privilege changes

Patch Information

Chamilo has released version 1.11.36 which addresses this SQL Injection vulnerability. The patch corrects the input sanitization logic to ensure that escaping mechanisms are not inadvertently bypassed. Organizations should upgrade to this version as soon as possible. For detailed patch information, refer to the GitHub Release v1.11.36 and the GitHub Security Advisory GHSA-5ggx-x2cv-4h44.

Workarounds

• Restrict access to the statistics AJAX endpoint using web server configuration (e.g., IP whitelisting)
• Implement additional input validation at the web server or reverse proxy level to block SQL injection patterns
• Temporarily disable the statistics functionality until the patch can be applied
• Deploy a Web Application Firewall with SQL injection detection rules as an additional layer of protection