pysaml2 version 4.4.0 and older accept any password when run with python optimizations enabled. This allows attackers to log in as any user without knowing their password.
An entity expansion vulnerability was found in python-pysaml2.
Upstream patch:
https://github.com/rohe/pysaml2/commit/6e09a25d9b4b7aa7a506853210a9a14100b8bc9b
References:
http://seclists.org/oss-sec/2017/q1/140