Critical MySQL CVE-2018-2696 & Related Vulnerabilities: Impact, Exploits, and Fixes

Overview

Oracle security advisory addresses 25 MySQL service vulnerabilities. The most critical is CVE‑2018‑2696, which allows remote denial‑of‑service without authentication.

Vulnerability Details

CVE‑2018‑2562 – MySQL Partitioning Component

Impact: MySQL 5.5.58 and earlier, 5.6.38 and earlier, 5.7.19 and earlier. Allows low‑privilege users to cause denial‑of‑service via multiple protocols and to perform unauthorized UPDATE, INSERT, or DELETE operations. MariaDB branches are also affected.

CVE‑2018‑2591 – MySQL Partitioning Component (MariaDB Safe)

Impact: MySQL 5.6.38 and earlier, 5.7.19 and earlier. Allows low‑privilege denial‑of‑service attacks. MariaDB branches are not affected.

CVE‑2018‑2696 – sha256_password Authentication DoS

The sha256_password plugin does not limit password length and passes the raw password to my_crypt_genhash() for SHA‑256 hashing. An excessively long password exhausts CPU resources, and because the implementation uses alloca(), it can cause stack overflow, memory leakage, process crashes, and potentially remote code execution. Affected versions: MySQL ≤ 5.6.38 and MySQL ≤ 5.7.20. MariaDB branches are not affected.

Exploitation Conditions

A proof‑of‑concept can be executed remotely without authentication. The PoC has not been publicly released.

Detection

Verify the version of the deployed MySQL server against the vulnerable version ranges listed above.

Mitigation

Upgrade to patched releases provided by Oracle:

MySQL 5.6.39 – https://dev.mysql.com/downloads/mysql/5.6.html

MySQL 5.7.21 – https://dev.mysql.com/downloads/mysql/5.7.html

Consider migrating to MariaDB, which is binary‑compatible with MySQL and provides additional features.

References

Oracle Security Advisory (detailed) – http://www.oracle.com/technetwork/security-advisory/cpujan2018verbose-3236630.html#MSQL

Red Hat CVE Tracker – https://access.redhat.com/security/cve/CVE-2018-2696

Oracle Advisory Summary – http://www.oracle.com/technetwork/security-advisory/cpujan2018-3236628.html

SecurityTracker entry – https://securitytracker.com/id/1040216