CVE-2004-0956 in MySQL
Summary
by MITRE
MySQL before 4.0.20 allows remote attackers to cause a denial of service (application crash) via a MATCH AGAINST query with an opening double quote but no closing double quote.
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Analysis
by VulDB Data Team • 07/07/2025
The vulnerability described in CVE-2004-0956 represents a classic buffer over-read condition within the MySQL database management system that existed prior to version 4.0.20. This flaw specifically manifests when processing full-text search queries using the MATCH AGAINST syntax, where an attacker can craft a malicious query containing an opening double quote character without a corresponding closing quote. The absence of proper input validation and sanitization in the MySQL query parser creates a scenario where the application fails to handle malformed input gracefully, leading to unpredictable behavior and ultimately application instability.
The technical implementation of this vulnerability stems from inadequate string parsing and quote handling mechanisms within MySQL's full-text search functionality. When the database engine encounters a MATCH AGAINST query with improperly terminated quoted strings, it attempts to process the malformed input without sufficient boundary checking. This results in memory access violations where the parser reads beyond allocated buffer boundaries, causing the application to crash and terminate unexpectedly. The flaw operates at the application layer and requires no authentication or elevated privileges to exploit, making it particularly dangerous as it can be triggered by any remote user with access to the database service. This type of vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions that can lead to denial of service and information disclosure.
The operational impact of CVE-2004-0956 extends beyond simple application instability to encompass broader security implications for database availability and system reliability. Organizations running vulnerable MySQL versions face potential disruption of database services, which can cascade into larger system outages depending on the criticality of the affected database. The vulnerability creates an attack surface that can be exploited by malicious actors to perform denial of service attacks against database servers, potentially causing significant business disruption. From an attacker perspective, this vulnerability aligns with the MITRE ATT&CK framework's privilege escalation and denial of service tactics, as it allows unauthorized users to compromise service availability without requiring additional access privileges. The exploitability of this vulnerability is enhanced by the fact that it does not require specific authentication credentials, making it a particularly attractive target for automated scanning and exploitation tools.
Mitigation strategies for CVE-2004-0956 focus primarily on immediate patching and system hardening measures. The most effective remediation involves upgrading to MySQL version 4.0.20 or later, where the parsing logic has been corrected to properly handle malformed quoted strings in full-text search queries. System administrators should also implement input validation measures at the application level to sanitize all user-supplied data before it reaches the database engine, particularly for full-text search operations. Network-level protections such as firewall rules and database access controls can help limit exposure by restricting direct access to database services from untrusted networks. Additionally, monitoring and logging mechanisms should be enhanced to detect unusual query patterns that might indicate attempted exploitation of this vulnerability, providing early warning capabilities for potential attacks. Organizations should also consider implementing database activity monitoring tools that can identify and alert on malformed queries that could trigger similar buffer over-read conditions in other database components.