CVE-2025-12256: Online Event Judging System SQLi Flaw

CVE-2025-12256 Overview

CVE-2025-12256 is a SQL injection vulnerability in code-projects Online Event Judging System 1.0, developed by Carmelo. The flaw resides in /edit_contestant.php, where the contestant_id parameter is passed to the backend database query without proper sanitization. Authenticated remote attackers can manipulate this parameter to inject arbitrary SQL statements. The weakness is classified under [CWE-74] (Improper Neutralization of Special Elements in Output Used by a Downstream Component). Public disclosure of the exploit details increases the likelihood of opportunistic attacks against exposed instances.

Critical Impact
Remote attackers with low-level privileges can manipulate the contestant_id parameter to execute arbitrary SQL queries against the application database, potentially exposing or modifying contestant records.

Affected Products

Carmelo Online Event Judging System 1.0
/edit_contestant.php endpoint
Deployments exposing the application to untrusted networks

Discovery Timeline

2025-10-27 - CVE-2025-12256 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-12256

Vulnerability Analysis

The vulnerability exists in the edit_contestant.php script of the Online Event Judging System. The contestant_id argument is received from the HTTP request and concatenated into a SQL query without parameterization or input validation. Attackers can append SQL meta-characters and clauses to alter query semantics. Because the attack vector is network-based and requires only low-level privileges, the barrier to exploitation is minimal for any user with valid application credentials.

According to the VulDB submission referenced in the NVD record, technical details and proof-of-concept material have been made available to the public, raising exposure risk for unpatched deployments.

Root Cause

The root cause is the use of unsanitized user input in a dynamic SQL statement. The application constructs queries by string concatenation rather than using prepared statements with bound parameters. This pattern, captured under [CWE-74], allows special characters such as single quotes, semicolons, and SQL keywords to be interpreted as query syntax rather than data values.

Attack Vector

An authenticated attacker issues an HTTP request to /edit_contestant.php with a crafted contestant_id value containing SQL payloads. Typical payloads use boolean-based, union-based, or time-based blind techniques to extract data or modify records. No user interaction is required beyond submitting the malicious request. See the GitHub CVE Issue Tracker and VulDB #329927 for technical details.

Detection Methods for CVE-2025-12256

Indicators of Compromise

HTTP requests to /edit_contestant.php containing SQL meta-characters such as ', --, UNION, SLEEP(, or OR 1=1 in the contestant_id parameter
Unexpected database errors logged by the PHP application or backend MySQL/MariaDB server
Anomalous read activity against contestant or user tables originating from the web application service account

Detection Strategies

Inspect web server access logs for non-numeric values in the contestant_id query string or POST body
Deploy a web application firewall (WAF) rule set tuned for SQL injection signatures targeting the edit_contestant.php endpoint
Correlate database query errors with the source HTTP request to identify probing attempts

Monitoring Recommendations

Forward web server, PHP error, and database logs to a centralized analytics platform for correlation
Alert on repeated 500-series responses from /edit_contestant.php within short time windows
Monitor outbound network traffic from the database host for unexpected connections that may indicate data exfiltration

How to Mitigate CVE-2025-12256

Immediate Actions Required

Restrict access to the Online Event Judging System to trusted networks or VPN users until a fix is applied
Audit application accounts and revoke credentials that are no longer required to reduce the pool of potential attackers
Review database logs and contestant records for evidence of tampering or unauthorized queries

Patch Information

No vendor security advisory or official patch has been published in the references associated with this CVE. Operators should monitor the Code Projects Resource Hub and the GitHub CVE Issue Tracker for updates. Until a vendor fix is available, code-level remediation requires replacing dynamic SQL concatenation in edit_contestant.php with prepared statements using PDO or mysqli parameter binding.

Workarounds

Place a WAF in front of the application and enforce strict signature-based filtering on the contestant_id parameter
Add server-side input validation that rejects any contestant_id value that is not a positive integer before the query executes
Restrict the database account used by the application to the minimum privileges required, removing rights to sensitive tables and administrative operations

bash

# Example nginx rule to reject non-numeric contestant_id values
location /edit_contestant.php {
    if ($arg_contestant_id !~ "^[0-9]+$") {
        return 400;
    }
}