CVE-2026-5326: Leave Application System Auth Bypass Flaw

CVE-2026-5326 Overview

A vulnerability was identified in SourceCodester Leave Application System 1.0 affecting the User Information Handler component. The flaw exists in the file /index.php?page=manage_user, where improper authorization controls allow manipulation of the ID argument to bypass access restrictions. This Insecure Direct Object Reference (IDOR) vulnerability enables unauthorized access to user information and can be exploited remotely without authentication.

Critical Impact

Remote attackers can exploit this authorization bypass to access or manipulate user data belonging to other users in the Leave Application System, potentially compromising employee personal information and leave records.

Affected Products

• SourceCodester Leave Application System 1.0
• PHP/SQLite3-based Leave Application System installations
• Systems exposing /index.php?page=manage_user endpoint

Discovery Timeline

• April 2, 2026 - CVE-2026-5326 published to NVD
• April 2, 2026 - Last updated in NVD database

Technical Details for CVE-2026-5326

Vulnerability Analysis

This vulnerability represents an Insecure Direct Object Reference (IDOR) flaw classified under CWE-285 (Improper Authorization). The Leave Application System fails to properly validate whether authenticated users have authorization to access or modify resources identified by the ID parameter in the User Information Handler component.

When a user accesses the manage_user page, the application accepts an ID parameter that directly references user records in the underlying SQLite3 database. The application does not verify that the requesting user has legitimate access rights to the specified user record, allowing any authenticated user to view or modify other users' information simply by changing the ID value in the request.

The vulnerability is network-accessible and requires no user interaction, making it trivially exploitable by anyone with basic HTTP request manipulation capabilities. The exploit for this vulnerability has been publicly disclosed, increasing the risk of widespread abuse.

Root Cause

The root cause is improper authorization validation in the User Information Handler. The application uses the user-supplied ID parameter to directly query the database without implementing proper access control checks. This violates the principle of least privilege and fails to enforce object-level authorization, allowing horizontal privilege escalation between user accounts.

Attack Vector

The attack is executed remotely over the network by manipulating HTTP requests to the vulnerable endpoint. An attacker can enumerate valid user IDs and access sensitive user information by modifying the ID parameter in requests to /index.php?page=manage_user. The attack does not require any special privileges or user interaction, as the vulnerable endpoint processes the manipulated parameter without proper authorization checks.

The vulnerability can be exploited by intercepting legitimate requests and modifying the ID parameter value to reference other users' records. Attackers may iterate through sequential ID values to discover and access all user accounts in the system. For detailed technical analysis, see the Medium Blog Post on IDOR.

Detection Methods for CVE-2026-5326

Indicators of Compromise

• Unusual patterns of access to /index.php?page=manage_user with varying ID parameters from a single session
• Sequential enumeration attempts against user ID values in HTTP request logs
• Access attempts to user records outside the authenticated user's normal scope
• Anomalous spikes in requests to the User Information Handler component

Detection Strategies

• Monitor web application logs for repeated requests to manage_user endpoint with different ID values
• Implement behavioral analysis to detect ID parameter enumeration patterns
• Configure Web Application Firewall (WAF) rules to flag suspicious IDOR-like request patterns
• Deploy application-level logging to track authorization failures and access anomalies

Monitoring Recommendations

• Enable detailed access logging for the Leave Application System
• Set up alerts for bulk access attempts to user management endpoints
• Correlate authentication logs with resource access patterns to identify unauthorized access
• Review audit logs regularly for signs of horizontal privilege escalation attempts

How to Mitigate CVE-2026-5326

Immediate Actions Required

• Restrict access to the /index.php?page=manage_user endpoint to authorized administrative users only
• Implement server-side authorization checks to validate user access rights before processing ID parameters
• Review application access logs for signs of prior exploitation
• Consider taking the Leave Application System offline until proper access controls can be implemented

Patch Information

No official patch information is currently available from the vendor. Organizations should monitor SourceCodester for security updates. For additional vulnerability details and community-contributed information, refer to the VulDB Vulnerability #354657 entry.

Workarounds

• Implement indirect object references using session-bound tokens instead of direct database IDs
• Add server-side authorization checks that verify the requesting user has permission to access the specified resource
• Deploy a Web Application Firewall (WAF) with rules to detect and block IDOR exploitation attempts
• Restrict access to administrative functions through network segmentation or IP whitelisting

# Example Apache configuration to restrict access to vulnerable endpoint
<Location "/index.php">
    <If "%{QUERY_STRING} =~ /page=manage_user/">
        Require ip 192.168.1.0/24
        # Restrict to internal admin network only
    </If>
</Location>