CVE-2021-2178 in MySQL Server
Summary
by MITRE • 04/23/2021
Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Replication). Supported versions that are affected are 5.7.32 and prior and 8.0.22 and prior. Easily exploitable vulnerability allows low 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 3.1 Base Score 6.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
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Analysis
by VulDB Data Team • 04/26/2021
The vulnerability identified as CVE-2021-2178 represents a critical availability flaw within Oracle MySQL Server's replication component that affects multiple version ranges including 5.7.32 and earlier, as well as 8.0.22 and prior releases. This weakness manifests as a denial of service condition that can be triggered by low-privileged attackers who gain network access through various protocols. The vulnerability's classification as easily exploitable indicates that attackers with minimal privileges and network connectivity can successfully compromise the target MySQL server infrastructure. The CVSS base score of 6.5 reflects the significant availability impact, with the vector AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H demonstrating that network-based attacks require low access complexity, low privilege requirements, and can result in high availability impact without user interaction or scope changes.
The technical exploitation of this vulnerability occurs within the server replication subsystem where specific conditions trigger memory corruption or resource exhaustion that leads to server instability. Attackers can leverage this flaw to cause either a complete hang of the MySQL server process or frequent crashes that result in persistent service disruption. This type of vulnerability typically stems from inadequate input validation or memory management within the replication protocol handling code, creating opportunities for malformed replication events or commands to trigger system-level failures. The replication component is particularly susceptible because it processes data streams from multiple sources and must maintain synchronization between master and slave servers, making it a prime target for attackers seeking to disrupt database operations.
The operational impact of CVE-2021-2178 extends beyond simple service interruption to encompass potential data integrity concerns and business continuity risks for organizations relying on MySQL replication for high availability setups. When a MySQL server experiences frequent crashes or hangs due to this vulnerability, it can lead to cascading failures in dependent applications and services that depend on database availability. The complete denial of service condition means that database transactions cannot proceed normally, potentially causing application failures, data loss, or extended downtime periods that can severely impact business operations. Organizations using MySQL replication architectures face particular risk as this vulnerability can be exploited to target not just individual servers but entire replication chains that may span multiple geographic locations or server types.
Mitigation strategies for CVE-2021-2178 should prioritize immediate patching of affected MySQL versions to the latest stable releases that contain the necessary security fixes. Organizations should implement network segmentation and access controls to limit exposure of MySQL servers to untrusted networks while maintaining strict authentication mechanisms for replication connections. Monitoring solutions should be deployed to detect unusual replication behavior or connection patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-121 which addresses stack-based buffer overflow conditions, and may also relate to ATT&CK technique T1499.004 for network denial of service attacks. Regular vulnerability assessments and penetration testing should be conducted to identify similar weaknesses in database infrastructure, while incident response procedures should be updated to address potential replication-based denial of service scenarios that could compromise overall system availability.