bitcoind and Bitcoin-Qt prior to 0.17.1 allow injection of arbitrary data into the debug log via an RPC call.
Bitcoin Core 0.14.x before 0.14.3, 0.15.x before 0.15.2, and 0.16.x before 0.16.3 and Bitcoin Knots 0.14.x through 0.16.x before 0.16.3 allow a remote denial of service (application crash) exploitable by miners via duplicate input. An attacker can make bitcoind or Bitcoin-Qt crash.