CVE-2025-4736: Daily Expense Tracker SQL Injection Flaw

CVE-2025-4736 Overview

A critical SQL injection vulnerability has been identified in PHPGurukul Daily Expense Tracker version 1.1. The vulnerability exists in the /register.php file where improper handling of the email parameter allows attackers to inject malicious SQL queries. This flaw can be exploited remotely without authentication, potentially compromising the entire database containing user financial records and personal information.

Critical Impact
Unauthenticated attackers can exploit this SQL injection vulnerability remotely to access, modify, or delete sensitive financial data stored in the Daily Expense Tracker application database.

Affected Products

PHPGurukul Daily Expense Tracker version 1.1
anujk305 daily_expense_tracker

Discovery Timeline

2025-05-16 - CVE-2025-4736 published to NVD
2025-05-27 - Last updated in NVD database

Technical Details for CVE-2025-4736

Vulnerability Analysis

This SQL injection vulnerability stems from insufficient input validation in the user registration functionality of PHPGurukul Daily Expense Tracker. The /register.php endpoint fails to properly sanitize or parameterize user-supplied input in the email argument before incorporating it into SQL queries. This allows attackers to manipulate the application's database queries by injecting malicious SQL code through the email field.

The vulnerability is classified under CWE-89 (Improper Neutralization of Special Elements used in an SQL Command) and CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component). The exploit has been publicly disclosed, increasing the urgency for remediation.

Root Cause

The root cause of this vulnerability is the direct concatenation of user-supplied input into SQL queries without proper sanitization, parameterization, or use of prepared statements. The email parameter in /register.php is passed directly to database queries, allowing special SQL characters and commands to be interpreted as part of the query structure rather than as data values.

Attack Vector

The vulnerability can be exploited remotely over the network without requiring any authentication or user interaction. An attacker can craft a malicious HTTP request to the /register.php endpoint with a specially crafted email parameter containing SQL injection payloads. This allows the attacker to:

Extract sensitive data from the database including user credentials and financial records
Modify or delete existing database entries
Bypass authentication mechanisms
Potentially escalate privileges within the application
In some configurations, execute operating system commands

The attack targets the registration form where the email field is processed, making it particularly dangerous as registration pages are typically accessible to unauthenticated users.

Detection Methods for CVE-2025-4736

Indicators of Compromise

Unusual or malformed email addresses in registration logs containing SQL syntax characters such as single quotes ('), double dashes (--), semicolons (;), or UNION statements
Database query errors or exceptions logged by the application
Unexpected database access patterns or queries targeting system tables
Anomalous data extraction or bulk data access from user or expense tables

Detection Strategies

Implement Web Application Firewall (WAF) rules to detect and block SQL injection patterns in HTTP POST requests to /register.php
Enable database query logging and monitor for suspicious query patterns including UNION-based injection attempts
Deploy intrusion detection systems (IDS) with signatures for common SQL injection attack vectors
Configure application-level logging to capture and alert on malformed input in the email parameter

Monitoring Recommendations

Monitor web server access logs for repeated requests to /register.php with unusual parameter lengths or encoding
Set up alerts for database authentication failures or permission denied errors that may indicate exploitation attempts
Track failed registration attempts with invalid email formats that may contain injection payloads
Review database audit logs for unauthorized SELECT statements or data exfiltration patterns

How to Mitigate CVE-2025-4736

Immediate Actions Required

Remove or disable the PHPGurukul Daily Expense Tracker application from production environments until a patch is available
Implement input validation at the web server level using WAF rules to block SQL injection attempts
Restrict network access to the application using firewall rules to limit exposure
Review database logs for evidence of prior exploitation and consider database integrity verification

Patch Information

No official vendor patch has been released at this time. Organizations using PHPGurukul Daily Expense Tracker should monitor the PHP Gurukul Security Resource for updates and security advisories. Additional technical details are available via the GitHub Issue Discussion and VulDB #309038.

Workarounds

Implement prepared statements and parameterized queries by modifying the /register.php source code to use PDO or MySQLi with bound parameters
Deploy a Web Application Firewall (WAF) with SQL injection protection rules enabled for the affected endpoint
Add server-side input validation to enforce strict email format checking using regular expressions before database operations
Consider using an alternative expense tracking solution until the vulnerability is officially patched

bash

# Configuration example - Apache mod_security rule to block SQL injection in email parameter
SecRule ARGS:email "@detectSQLi" "id:1001,phase:2,deny,status:403,msg:'SQL Injection attempt detected in email parameter',log,auditlog"