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 via an invalid salt or, when FIPS-140 is enabled, a DES or MD5 encrypted password, which triggers a NULL pointer dereference.