parser.c in libxml2 before 2.9.2 does not properly prevent entity expansion even when entity substitution has been disabled, which allows context-dependent…

parser.c in libxml2 before 2.9.2 does not properly prevent entity expansion even when entity substitution has been disabled, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted XML document containing a large number of nested entity references, a variant of the "billion laughs" attack.