Oracle » Mysql » 5.5.20 : Security Vulnerabilities, CVEs, (Gain Privilege)

Unspecified vulnerability in Oracle MySQL 5.6.27 and earlier and 5.7.9 allows remote authenticated users to affect availability via unknown vectors related to Optimizer.

sql/password.c in Oracle MySQL 5.1.x before 5.1.63, 5.5.x before 5.5.24, and 5.6.x before 5.6.6, and MariaDB 5.1.x before 5.1.62, 5.2.x before 5.2.12, 5.3.x before 5.3.6, and 5.5.x before 5.5.23, when running in certain environments with certain implementations of the memcmp function, allows remote attackers to bypass authentication by repeatedly authenticating with the same incorrect password, which eventually causes a token comparison to succeed due to an improperly-checked return value.