Description: Stefan Esser has reported a vulnerability in PHP, which can be exploited by malicious people to bypass certain security restrictions.
The vulnerability is caused due to a race condition when calling the system's "crypt()" function on multi threaded systems. The problem is that two threads validating passwords at the same time are using the same internal memory. This can lead to a successful authentication with an invalid password.
The vulnerability is reported in PHP 5 prior to 5.2.1 on UNIX systems. PHP 4 and PHP 5 on Windows systems may also be affected.
Solution: Do not use the "crypt()" function in a multi threaded environment.
PHP 5 for UNIX systems:
Update to version 5.2.1 or later.
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