CVE-2017-3243 in MySQL Server
Summary
by MITRE
Vulnerability in the MySQL Server component of Oracle MySQL (subcomponent: Server: Charsets). Supported versions that are affected are 5.5.53 and earlier. Difficult to exploit vulnerability allows high privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS v3.0 Base Score 4.4 (Availability impacts).
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Analysis
by VulDB Data Team • 05/15/2026
The vulnerability identified as CVE-2017-3243 resides within the MySQL Server component of Oracle MySQL, specifically within the Server: Charsets subcomponent. This weakness affects MySQL versions 5.5.53 and earlier, representing a significant security concern for organizations utilizing these older database systems. The vulnerability's classification as difficult to exploit indicates that while it requires specific conditions and privileges to be successfully leveraged, the potential impact remains severe enough to warrant immediate attention. The attack vector requires a high-privileged attacker with network access through multiple protocols, suggesting that the vulnerability could be exploited by individuals who already possess elevated system credentials or those who can establish network connections to the target system.
The technical flaw manifests as a weakness in how MySQL Server processes character set handling, creating a condition where malicious input can trigger abnormal behavior in the database server. This particular vulnerability falls under the category of availability impact, as demonstrated by the CVSS v3.0 Base Score of 4.4, which indicates a moderate severity level for availability concerns. The exploitation of this vulnerability results in the ability to cause either a complete denial of service through hanging or frequent crashes that repeat consistently, effectively rendering the MySQL Server unavailable to legitimate users and applications that depend on database operations. This type of vulnerability directly impacts the operational continuity of systems that rely on MySQL for data management and application functionality.
The operational impact of CVE-2017-3243 extends beyond simple service disruption, as database server downtime can cascade through entire application ecosystems that depend on MySQL for their core operations. Organizations experiencing this vulnerability may face significant business disruption, particularly in environments where database availability is critical for transaction processing, user authentication, or data integrity services. The fact that this vulnerability can be exploited through multiple protocols suggests that attackers may utilize various network entry points to attempt exploitation, making it more challenging to defend against through traditional network segmentation approaches. This characteristic aligns with the ATT&CK framework's concept of multiple access vectors and emphasizes the importance of comprehensive network security measures.
From a defensive standpoint, organizations should prioritize upgrading to MySQL versions that are not affected by this vulnerability, specifically moving beyond version 5.5.53 to ensure protection against exploitation. The implementation of network segmentation and access controls can help limit the attack surface by restricting network access to MySQL servers, thereby reducing the likelihood of exploitation by unauthorized users. Additionally, monitoring for unusual network traffic patterns or database server behavior can aid in early detection of potential exploitation attempts. The vulnerability's classification as a character set processing issue also suggests that input validation and sanitization measures should be enhanced to prevent malformed character set data from reaching the vulnerable components. Organizations should also consider implementing database activity monitoring solutions that can detect anomalous behavior patterns consistent with the exploitation of availability-focused vulnerabilities. The remediation process should include not only the software update but also comprehensive testing to ensure that the upgrade does not introduce compatibility issues with existing applications or database configurations. This vulnerability serves as a reminder of the critical importance of maintaining up-to-date database software and implementing robust security practices to protect against exploits that target fundamental server components.