CVE-2009-4484 in mysql
Summary
by MITRE
Multiple stack-based buffer overflows in the CertDecoder::GetName function in src/asn.cpp in TaoCrypt in yaSSL before 1.9.9, as used in mysqld in MySQL 5.0.x before 5.0.90, MySQL 5.1.x before 5.1.43, MySQL 5.5.x through 5.5.0-m2, and other products, allow remote attackers to execute arbitrary code or cause a denial of service (memory corruption and daemon crash) by establishing an SSL connection and sending an X.509 client certificate with a crafted name field, as demonstrated by mysql_overflow1.py and the vd_mysql5 module in VulnDisco Pack Professional 8.11. NOTE: this was originally reported for MySQL 5.0.51a.
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Analysis
by VulDB Data Team • 04/07/2025
This vulnerability represents a critical stack-based buffer overflow in the CertDecoder::GetName function within the yaSSL cryptographic library implementation. The flaw exists in the ASN.1 parsing logic responsible for processing X.509 client certificates during SSL/TLS handshake procedures. The vulnerability affects multiple MySQL versions including 5.0.x through 5.5.x releases, with the specific issue manifesting when processing crafted certificate name fields during SSL connection establishment. This represents a classic buffer overflow condition where insufficient input validation allows attackers to write beyond allocated stack memory boundaries, potentially leading to arbitrary code execution or daemon crashes. The vulnerability is particularly concerning as it operates at the SSL/TLS protocol level, making it accessible to remote attackers without requiring local system access or elevated privileges.
The technical implementation of this vulnerability stems from improper bounds checking within the ASN.1 decoding routine that processes X.509 certificate attributes. When a client presents an SSL certificate containing a specially crafted name field, the CertDecoder::GetName function fails to properly validate the length of the input data against the allocated buffer space. This allows attackers to overflow the stack buffer and overwrite adjacent memory locations including return addresses and function pointers. The vulnerability is categorized under CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows where data is written beyond the bounds of a stack-allocated buffer. The attack vector requires establishing an SSL connection and presenting a malicious certificate, making it particularly dangerous in environments where SSL/TLS is actively used for database authentication and communication.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to include potential remote code execution capabilities. When exploited successfully, attackers can manipulate the program flow by overwriting return addresses and executing arbitrary code within the context of the mysql daemon process. This represents a significant compromise of system security as the mysql daemon typically runs with elevated privileges and has access to sensitive database information. The vulnerability affects database servers that rely on SSL/TLS for client authentication, making it particularly relevant for production environments where database security is paramount. Additionally, the vulnerability's presence in multiple MySQL versions indicates a widespread exposure risk across various deployment scenarios and system configurations. The specific demonstration tools mentioned including mysql_overflow1.py and the vd_mysql5 module in VulnDisco Pack Professional 8.11 confirm that this vulnerability is not theoretical but has been actively exploited in real-world scenarios.
Mitigation strategies for this vulnerability require immediate patching of affected MySQL installations to versions that include the yaSSL library fixes. Organizations should prioritize updating their MySQL deployments to versions 5.0.90, 5.1.43, or later 5.5.x releases that contain the necessary cryptographic library updates. Additionally, network segmentation and firewall rules should be implemented to restrict unnecessary SSL/TLS access to database servers, reducing the attack surface. System administrators should monitor for suspicious SSL connection attempts and certificate validation failures that might indicate exploitation attempts. The vulnerability also highlights the importance of regularly updating cryptographic libraries and third-party components within database systems, as this flaw existed in the yaSSL implementation rather than being specific to MySQL's core functionality. Organizations should implement security monitoring procedures to detect potential exploitation attempts and maintain comprehensive backup and recovery procedures to address potential system compromise scenarios. This vulnerability demonstrates the critical need for proper input validation in cryptographic libraries and the importance of following security best practices such as those outlined in the OWASP Top Ten and NIST cybersecurity guidelines for database system security management.