CVE-2025-31403: Booking Calendar SQL Injection Flaw

CVE-2025-31403 Overview

CVE-2025-31403 is a critical Blind SQL Injection vulnerability affecting the Booking Calendar and Notification WordPress plugin developed by shiptrack. This vulnerability allows unauthenticated attackers to execute arbitrary SQL queries against the backend database by injecting malicious SQL commands through improperly sanitized input fields. The blind nature of this injection means attackers can extract sensitive data through true/false responses or time-based inference techniques.

Critical Impact
Unauthenticated attackers can exfiltrate sensitive database contents including user credentials, personal information, and WordPress configuration data without direct visibility of query results.

Affected Products

Booking Calendar and Notification plugin versions up to and including 4.0.3
WordPress installations running vulnerable versions of the plugin
All WordPress sites with the shiptrack Booking Calendar and Notification plugin installed

Discovery Timeline

2025-04-04 - CVE-2025-31403 published to NVD
2025-04-07 - Last updated in NVD database

Technical Details for CVE-2025-31403

Vulnerability Analysis

This vulnerability stems from improper neutralization of special elements used in SQL commands (CWE-89). The Booking Calendar and Notification plugin fails to adequately sanitize user-supplied input before incorporating it into SQL queries executed against the WordPress database. This allows attackers to manipulate query logic and extract data through blind SQL injection techniques.

Blind SQL injection differs from traditional SQL injection in that the attacker cannot directly observe query results. Instead, they must infer information based on application behavior—either through boolean-based techniques (observing different responses for true/false conditions) or time-based techniques (measuring response delays introduced by conditional database sleep commands).

The vulnerability is accessible over the network without any authentication requirements, significantly expanding the attack surface. Successful exploitation could lead to complete compromise of database confidentiality and partial availability impact through resource exhaustion or data manipulation.

Root Cause

The root cause is improper input validation and sanitization within the plugin's database query construction. The plugin directly incorporates user-controlled input into SQL statements without using parameterized queries or prepared statements. WordPress provides the $wpdb->prepare() method specifically designed to prevent SQL injection by properly escaping and quoting user input, but this security control was not implemented in the vulnerable code paths.

Attack Vector

The attack vector is network-based, allowing remote unauthenticated attackers to exploit this vulnerability. Attackers can craft malicious HTTP requests containing SQL injection payloads targeting the vulnerable plugin endpoints. The blind nature requires attackers to use inference techniques to extract data character-by-character, though automated tools like SQLMap can significantly accelerate this process.

Typical exploitation involves sending requests with payloads that cause conditional database behavior. For boolean-based blind injection, the attacker observes whether the application returns different content based on injected true or false conditions. For time-based blind injection, the attacker uses database-specific sleep functions (like MySQL's SLEEP() or BENCHMARK()) to introduce measurable delays when conditions are met.

Detection Methods for CVE-2025-31403

Indicators of Compromise

Unusual database query patterns containing SQL keywords like UNION, SELECT, SLEEP, BENCHMARK, or WAITFOR in web server logs
Repeated requests to booking calendar endpoints with incrementing or binary-search-style parameter values
Abnormally high database CPU usage or query execution times indicating time-based injection attempts
Web application firewall logs showing blocked SQL injection patterns targeting the plugin

Detection Strategies

Deploy web application firewall (WAF) rules specifically designed to detect SQL injection patterns in request parameters
Enable WordPress database query logging and monitor for suspicious query patterns or errors
Implement real-time log analysis to detect automated SQL injection tool signatures (SQLMap, Havij, etc.)
Review access logs for unusual patterns of requests to Booking Calendar and Notification plugin endpoints

Monitoring Recommendations

Configure database monitoring to alert on queries with excessive execution times that may indicate time-based injection
Set up anomaly detection for request patterns showing characteristics of automated exploitation tools
Monitor WordPress error logs for SQL syntax errors that may indicate injection attempts
Implement endpoint-specific rate limiting on booking calendar functionality to slow automated attacks

How to Mitigate CVE-2025-31403

Immediate Actions Required

Update the Booking Calendar and Notification plugin immediately if a patched version is available
Temporarily deactivate the plugin if no patch is available and the functionality is not critical
Implement WAF rules to block common SQL injection patterns targeting the vulnerable endpoints
Review database access logs for evidence of prior exploitation attempts

Patch Information

Organizations should check for updates through the WordPress plugin repository or the vendor's official channels. According to the Patchstack SQL Injection Advisory, versions through 4.0.3 are confirmed vulnerable. Administrators should update to any version released after the vulnerability disclosure that addresses this issue.

Workarounds

Deactivate the Booking Calendar and Notification plugin until a security patch is applied
Implement virtual patching through a web application firewall with SQL injection detection rules
Restrict access to booking calendar functionality to authenticated users only if possible
Consider using an alternative booking calendar plugin with a strong security track record while awaiting a fix