CVE-2011-5049 in MySQL
Summary
by MITRE
MySQL 5.5.8, when running on Windows, allows remote attackers to cause a denial of service (NULL pointer dereference) via a crafted packet to TCP port 3306.
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Analysis
by VulDB Data Team • 03/18/2025
The vulnerability identified as CVE-2011-5049 represents a critical denial of service flaw affecting MySQL database servers version 5.5.8 when operating on Windows platforms. This issue manifests through a NULL pointer dereference condition that occurs when the database server processes specially crafted network packets transmitted to its default listening port 3306. The vulnerability exploits a fundamental flaw in the server's packet handling mechanism, specifically within the Windows-specific implementation of the MySQL protocol parser. Attackers can leverage this weakness by sending malformed or crafted data packets to the target MySQL server, triggering an unhandled NULL pointer access that results in immediate service termination and system instability.
The technical root cause of this vulnerability lies in insufficient input validation and error handling within the MySQL server's network protocol processing layer. When the server receives a malformed packet containing specific byte sequences or unexpected data structures, the parsing logic fails to properly validate pointer references before dereferencing them. This particular implementation flaw exists in the Windows-specific code path where the server handles incoming TCP connections and processes protocol messages. The NULL pointer dereference occurs during the processing of authentication or command packets, where the server attempts to access memory locations that have not been properly initialized or validated. This condition is particularly dangerous because it can be triggered remotely without requiring authentication or prior access to the system, making it an attractive target for malicious actors seeking to disrupt database services.
The operational impact of CVE-2011-5049 extends beyond simple service disruption, potentially affecting business continuity and data availability for organizations relying on MySQL databases. When exploited successfully, the vulnerability causes the MySQL service to crash and restart automatically, leading to temporary unavailability of database services that can result in transaction failures, application errors, and potential data loss. The remote exploit capability means that attackers can target vulnerable systems from anywhere on the network, making this vulnerability particularly dangerous in environments where database servers are exposed to untrusted networks or the internet. Organizations with high availability requirements face significant operational challenges as the service disruption can occur without warning, potentially affecting critical business applications that depend on database connectivity. The vulnerability also represents a potential vector for more sophisticated attacks, as the service disruption can be used to mask other malicious activities or create opportunities for further exploitation.
This vulnerability aligns with CWE-476, which describes NULL pointer dereference conditions in software implementations, and represents a classic example of inadequate error handling in network services. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to network disruption and service availability attacks. The flaw demonstrates how seemingly minor input validation issues can result in severe operational consequences, particularly in database systems that serve as foundational components for enterprise applications. Organizations should prioritize patching this vulnerability through official MySQL updates, while implementing network segmentation and firewall rules to restrict access to port 3306 where possible. Additionally, monitoring for unusual connection patterns or service restarts can help detect potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of thorough input validation and proper error handling in network-facing applications, particularly those handling sensitive business data in production environments.