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.
sarnold> NULL return from crypt() if the salt isn't sane
sarnold> Upgraded to medium, bug report shows remote attackers can disable
the sasl service by repeating the attack; THREADS=0 configuration is a
work-around that may help to prevent abuse.
mdeslaur> eglibc only returns NULL from crypt() in 2.17+, so quantal
mdeslaur> and older are not affected.