CVE-2007-1420 in MySQL
Summary
by MITRE
MySQL 5.x before 5.0.36 allows local users to cause a denial of service (database crash) by performing information_schema table subselects and using ORDER BY to sort a single-row result, which prevents certain structure elements from being initialized and triggers a NULL dereference in the filesort function.
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Analysis
by VulDB Data Team • 12/24/2024
This vulnerability exists in MySQL database versions 5.x prior to 5.0.36 and represents a critical denial of service flaw that can be exploited by local users. The issue stems from improper handling of certain query execution paths within the database engine's sorting functionality. When a local attacker executes specific information_schema table subselects combined with ORDER BY clauses on single-row results, the database engine fails to properly initialize critical internal structure elements. This initialization failure creates a condition where subsequent operations attempt to access uninitialized memory locations, leading to a NULL pointer dereference within the filesort function. The vulnerability specifically targets the database's query processing pipeline where sorting operations are performed on information_schema metadata tables, which contain system-level database information.
The technical exploitation of this vulnerability requires a local user account with access to the MySQL database system, as it cannot be leveraged remotely. Attackers must construct a specific query pattern that involves subselects from information_schema tables followed by ORDER BY operations on results that contain only a single row. This particular combination of operations triggers a code path that bypasses normal initialization routines for internal data structures used during sorting. The filesort function, which handles sorting operations for query results, attempts to access memory locations that were never properly initialized due to the specific query construction. This results in a segmentation fault or crash that terminates the database connection and potentially causes the entire MySQL service to become unavailable.
The operational impact of this vulnerability extends beyond simple service disruption as it can compromise database availability and potentially impact applications that depend on MySQL for data operations. Local users who can access the database system can reliably crash the database service by executing the crafted query, leading to unavailability of critical database functions. This denial of service condition affects all applications and services that rely on the affected MySQL instances, potentially causing cascading failures in larger system architectures. The vulnerability demonstrates a fundamental flaw in the database engine's resource management and initialization procedures, particularly when handling complex query execution paths involving metadata tables and sorting operations.
Mitigation strategies for this vulnerability include immediate patching of MySQL installations to version 5.0.36 or later, which contains the necessary code fixes to properly initialize required data structures during the problematic query execution path. System administrators should also implement proper access controls to limit local user privileges and restrict direct database access to authorized personnel only. Monitoring systems should be configured to detect unusual database query patterns that might indicate exploitation attempts, particularly around information_schema table usage with ORDER BY clauses. Additionally, organizations should conduct regular security assessments of their database environments to identify and remediate similar initialization and memory management issues. This vulnerability aligns with CWE-476 which addresses NULL pointer dereferences, and represents a classic example of improper initialization leading to memory safety issues. The ATT&CK framework would categorize this under privilege escalation and denial of service techniques, as local users can leverage this flaw to disrupt database operations and potentially gain further access to system resources through service disruption.