CVE-2021-47915: PHP Melody SQLi Vulnerability

CVE-2021-47915 Overview

CVE-2021-47915 is a SQL Injection vulnerability affecting PHP Melody version 3.0, a popular video content management system. The vulnerability exists in the video edit module where the vid parameter fails to properly validate and sanitize user input before incorporating it into SQL queries. This allows authenticated attackers to inject malicious SQL commands, potentially leading to unauthorized data access, data manipulation, or complete database compromise.

Critical Impact

Authenticated attackers can execute arbitrary SQL queries against the backend database, potentially extracting sensitive information, modifying data, or escalating privileges within the web application and underlying database management system.

Affected Products

• PHP Melody version 3.0

Discovery Timeline

• 2026-02-01 - CVE CVE-2021-47915 published to NVD
• 2026-02-03 - Last updated in NVD database

Technical Details for CVE-2021-47915

Vulnerability Analysis

This SQL Injection vulnerability (CWE-89) occurs in the video editing functionality of PHP Melody 3.0. The application accepts user-controlled input through the vid parameter without adequate validation or parameterized query handling. When an authenticated user submits a crafted request to the video edit module, the malicious SQL payload is directly concatenated into the database query, allowing the attacker to manipulate the query logic.

The vulnerability requires authentication to exploit, meaning attackers must first obtain valid credentials to the PHP Melody application. However, once authenticated, the exploitation is straightforward and can be performed through direct HTTP requests to the vulnerable endpoint.

Root Cause

The root cause of this vulnerability is improper input validation and the use of dynamic SQL query construction. The vid parameter value is directly incorporated into SQL statements without proper sanitization, escaping, or the use of prepared statements with parameterized queries. This classic SQL injection pattern allows attackers to break out of the intended query context and inject their own SQL commands.

Attack Vector

The attack is network-based and targets the video edit module's parameter handling. An authenticated attacker crafts a malicious request containing SQL injection payloads in the vid parameter. The vulnerability allows for both data extraction and data modification attacks.

The attack flow typically involves:

1. Authenticating to the PHP Melody application with valid credentials
2. Navigating to or directly requesting the video edit functionality
3. Manipulating the vid parameter with SQL injection payloads
4. Extracting database contents or modifying data through injected queries

For technical details on the vulnerability mechanism, refer to the Vulnerability Lab #2295 advisory.

Detection Methods for CVE-2021-47915

Indicators of Compromise

• Unusual or malformed requests to video edit endpoints containing SQL syntax characters such as single quotes, double dashes, or UNION keywords
• Database logs showing unexpected queries or errors related to video management tables
• Evidence of data exfiltration or unauthorized database access in application logs

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect SQL injection patterns in requests to the video edit module
• Monitor application logs for requests containing SQL keywords like UNION, SELECT, INSERT, DROP, or comment sequences
• Review database query logs for anomalous queries executed in the context of video editing operations
• Deploy intrusion detection systems with signatures for SQL injection attack patterns

Monitoring Recommendations

• Enable detailed logging for all requests to the PHP Melody administration interface
• Configure database auditing to track queries executed against video-related tables
• Set up alerting for authentication events followed by suspicious parameter manipulation
• Monitor for bulk data extraction patterns that may indicate successful exploitation

How to Mitigate CVE-2021-47915

Immediate Actions Required

• Review the PHP Melody Vulnerability Report for official patch information
• Restrict access to the video edit module to only trusted administrators
• Implement additional input validation at the web server or WAF level
• Review authentication logs for any suspicious access patterns

Patch Information

The vendor has published information regarding this vulnerability. Administrators should consult the official PHP Melody Vulnerability Report for patching instructions and updated software versions. Additional technical details are available from VulnCheck SQL Injection Advisory.

Workarounds

• Deploy a Web Application Firewall with SQL injection detection rules in front of the PHP Melody installation
• Implement network-level access controls to restrict access to the administrative interface
• Temporarily disable the video edit functionality until the patch can be applied
• Add server-side input validation to sanitize the vid parameter before query execution

# Example: ModSecurity WAF rule to block SQL injection attempts
SecRule ARGS:vid "@detectSQLi" \
    "id:1001,\
    phase:2,\
    deny,\
    status:403,\
    msg:'SQL Injection attempt detected in vid parameter',\
    log,\
    auditlog"