In Tor before 0.2.5.16 0.2.6 through 0.2.8 before 0.2.8.17 0.2.9 before 0.2.9.14 0.3.0 before 0.3.0.13 and 0.3.1 before 0.3.1.9 remote attackers can cause a denial of service (NULL pointer dereference and application crash) against directory authorities via a malformed descriptor aka TROVE-2017-010.