Cyrus SASL 2.1.23, 2.1.26, and earlier does not properly handle when a NULL value is returned upon an error by the crypt function as implemented in glibc 2.17 and later, which allows remote attackers to cause a denial of service (thread crash and consumption) via (1) an invalid salt or, when FIPS-140 is enabled, a (2) DES or (3) MD5 encrypted password, which triggers a NULL pointer dereference.
http://www.ubuntu.com/usn/USN-2755-1
http://www.openwall.com/lists/oss-security/2013/07/15/1
http://www.openwall.com/lists/oss-security/2013/07/13/1
http://www.openwall.com/lists/oss-security/2013/07/12/6
http://www.openwall.com/lists/oss-security/2013/07/12/3