The py-bcrypt module before 0.3 for Python does not properly handle concurrent memory access, which allows attackers to bypass authentication via multiple authentication requests, which trigger the password hash to be overwritten.
lists.fedoraproject.org/pipermail/package-announce/2013-April/101382.html
lists.fedoraproject.org/pipermail/package-announce/2013-April/101387.html
www.openwall.com/lists/oss-security/2013/03/26/2
www.securityfocus.com/bid/58702
exchange.xforce.ibmcloud.com/vulnerabilities/83039
github.com/advisories/GHSA-r838-q6jp-58xx