CVE-2009-4019 in mysql
Summary
by MITRE
mysqld in MySQL 5.0.x before 5.0.88 and 5.1.x before 5.1.41 does not (1) properly handle errors during execution of certain SELECT statements with subqueries, and does not (2) preserve certain null_value flags during execution of statements that use the GeomFromWKB function, which allows remote authenticated users to cause a denial of service (daemon crash) via a crafted statement.
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Analysis
by VulDB Data Team • 12/09/2024
The vulnerability described in CVE-2009-4019 represents a critical denial of service flaw affecting MySQL database servers running specific versions of the 5.0 and 5.1 release branches. This vulnerability stems from improper error handling mechanisms within the mysqld daemon component that processes database queries. The flaw manifests when executing certain SELECT statements that contain subqueries, where the server fails to properly manage error conditions during query execution. Additionally, the vulnerability involves the mishandling of null_value flags during execution of GeomFromWKB function calls, which are used for spatial data manipulation in MySQL's geographic information system capabilities. Both aspects of this vulnerability create conditions where maliciously crafted database statements can trigger unexpected server behavior.
The technical exploitation of this vulnerability requires an authenticated user with database access privileges to execute specifically crafted SQL statements against the affected MySQL server. When such statements are processed, the improper error handling during subquery execution causes the mysqld daemon to crash and restart, effectively creating a denial of service condition that disrupts database availability for legitimate users. The null_value flag preservation issue during GeomFromWKB function execution further compounds the vulnerability by potentially causing inconsistent state management within the database engine. This combination of error handling failures and state management issues creates multiple attack vectors that can be leveraged by malicious actors to disrupt database operations without requiring elevated privileges beyond standard database user access.
From a cybersecurity perspective, this vulnerability aligns with CWE-248, which addresses "Uncaught Exception" conditions in software applications, and represents a classic example of how improper error handling can lead to service disruption. The ATT&CK framework categorizes this as a Denial of Service technique under the "Resource Exhaustion" and "Execution Guardrails" domains, as the vulnerability specifically targets the daemon process availability. The impact extends beyond simple service interruption since database availability is fundamental to most enterprise applications, making this vulnerability particularly dangerous in production environments where database uptime is critical. Organizations relying on MySQL for mission-critical applications would face significant operational disruption if exploited, potentially affecting multiple dependent systems and services.
The recommended mitigation strategy involves immediate patching of affected MySQL installations to versions 5.0.88 and 5.1.41 or later, which contain the necessary fixes for both error handling and null_value flag preservation issues. System administrators should also implement network segmentation and access controls to limit the number of authenticated users who can execute potentially malicious statements. Database monitoring should be enhanced to detect unusual patterns of query execution that might indicate exploitation attempts. Additionally, organizations should consider implementing database firewalls or query filtering mechanisms that can identify and block suspicious statement patterns before they reach the database engine. Regular security assessments and vulnerability scanning should be conducted to ensure that no other similar issues exist within the database infrastructure, as this vulnerability demonstrates the importance of robust error handling in database systems.