CVE-2026-34973: phpMyFAQ Information Disclosure Flaw

CVE-2026-34973 Overview

CVE-2026-34973 is a SQL LIKE wildcard injection vulnerability affecting phpMyFAQ, an open source FAQ web application. Prior to version 4.1.1, the searchCustomPages() method in phpmyfaq/src/phpMyFAQ/Search.php uses real_escape_string() (via escape()) to sanitize the search term before embedding it in LIKE clauses. However, real_escape_string() does not escape SQL LIKE metacharacters % (match any sequence) and _ (match any single character). An unauthenticated attacker can inject these wildcards into search queries, causing them to match unintended records — including content that was not meant to be surfaced — resulting in information disclosure.

Critical Impact

Unauthenticated attackers can exploit SQL LIKE wildcard injection to enumerate and access sensitive FAQ content that was not intended to be publicly searchable, potentially exposing confidential information stored in the application.

Affected Products

• phpMyFAQ versions prior to 4.1.1
• phpMyFAQ Search module (phpmyfaq/src/phpMyFAQ/Search.php)
• Web installations using the searchCustomPages() functionality

Discovery Timeline

• 2026-04-02 - CVE-2026-34973 published to NVD
• 2026-04-02 - Last updated in NVD database

Technical Details for CVE-2026-34973

Vulnerability Analysis

This vulnerability falls under CWE-943: Improper Neutralization of Special Elements in Data Query Logic. The core issue stems from an incomplete input sanitization approach when handling user-supplied search terms in the phpMyFAQ application.

The application relies on MySQL's real_escape_string() function to sanitize user input before incorporating it into SQL LIKE clauses. While this function effectively escapes characters that could break out of string literals (such as single quotes and backslashes), it does not address the semantic meaning of LIKE-specific metacharacters.

In SQL LIKE pattern matching, the % character acts as a wildcard matching any sequence of characters (similar to * in shell globbing), while the _ character matches exactly one character. When these characters pass through sanitization unescaped, an attacker gains the ability to construct search queries that match far broader result sets than intended.

The network-accessible nature of this vulnerability means any unauthenticated user can craft malicious search queries to probe the FAQ database. The impact is information disclosure, where hidden or restricted content may be exposed through carefully constructed wildcard patterns.

Root Cause

The root cause is the improper selection of sanitization functions for the context in which user input is used. The escape() method wrapping real_escape_string() was designed to prevent SQL injection by escaping string-terminating characters, but LIKE clauses require additional escaping of pattern-matching metacharacters (% and _).

When user input containing these wildcards is passed to searchCustomPages(), the wildcards are preserved in the final SQL query, allowing pattern-based enumeration of database content. Proper mitigation requires escaping these characters with a backslash (e.g., \% and \_) or using parameterized queries with explicit ESCAPE clauses.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can submit crafted search queries through the phpMyFAQ search functionality:

The vulnerability can be exploited through the search interface by submitting wildcard characters directly. For example, submitting a search term containing only % would match all records in custom pages, while targeted patterns like admin% or confidential% could enumerate specific sensitive content. The _ wildcard enables character-by-character enumeration of content, allowing attackers to systematically discover hidden FAQ entries or configuration data that should not be publicly accessible.

For technical details on the vulnerable code paths, see the GitHub Security Advisory GHSA-gcp9-5jc8-976x.

Detection Methods for CVE-2026-34973

Indicators of Compromise

• Search queries containing standalone % or _ characters without accompanying search terms
• High volume of search requests from single IP addresses with incrementally varied wildcard patterns
• Search queries with patterns like %admin%, %password%, %config%, or %secret% targeting sensitive keywords
• Unusual access patterns to search functionality from automated tools or scripts

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block search queries consisting solely of SQL LIKE metacharacters
• Monitor application logs for search terms containing excessive wildcard characters or suspicious enumeration patterns
• Deploy anomaly detection for search functionality to identify brute-force enumeration attempts
• Review access logs for unusual search query patterns that deviate from normal user behavior

Monitoring Recommendations

• Enable detailed logging of all search queries including the raw search terms submitted by users
• Set up alerts for search queries that return abnormally large result sets compared to typical queries
• Monitor for sequential search requests that appear to be probing content systematically
• Implement rate limiting on the search endpoint to slow down enumeration attacks

How to Mitigate CVE-2026-34973

Immediate Actions Required

• Upgrade phpMyFAQ to version 4.1.1 or later immediately
• Review search logs for evidence of wildcard injection exploitation attempts
• Audit FAQ content to identify any sensitive information that may have been exposed
• Implement WAF rules to block search queries containing only wildcard characters as a temporary measure

Patch Information

The phpMyFAQ development team has addressed this vulnerability in version 4.1.1. The patch properly escapes SQL LIKE metacharacters before incorporating user input into search queries. Administrators should upgrade to this version or later to remediate the vulnerability.

For more information, see the phpMyFAQ 4.1.1 Release Notes and the GitHub Security Advisory.

Workarounds

• Implement input validation at the web server or application layer to strip or escape % and _ characters from search inputs
• Deploy a reverse proxy or WAF rule to sanitize search query parameters before they reach the application
• Temporarily disable the custom page search functionality if it is not critical to operations until the patch can be applied
• Restrict search functionality to authenticated users only to reduce the attack surface

# Example nginx configuration to block obvious wildcard-only searches
location /search {
    if ($arg_search ~ "^[%_]+$") {
        return 403;
    }
    proxy_pass http://phpmyfaq_backend;
}