Amazon Linux AMI Security Advisory: ALAS-2011-12
Advisory Release Date: 2014-09-14 14:32 Pacific
A signedness issue was found in the way the crypt() function in the PostgreSQL pgcrypto module handled 8-bit characters in passwords when using Blowfish hashing. Up to three characters immediately preceding a non-ASCII character (one with the high bit set) had no effect on the hash result, thus shortening the effective password length. This made brute-force guessing more efficient as several different passwords were hashed to the same value. (CVE-2011-2483 )
Note: Due to the CVE-2011-2483 fix, after installing this update some users may not be able to log in to applications that store user passwords, hashed with Blowfish using the PostgreSQL crypt() function, in a back-end PostgreSQL database. Unsafe processing can be re-enabled for specific passwords (allowing affected users to log in) by changing their hash prefix to "$2x$".
Run yum update postgresql to update your system.