Zcash 2.x allows an inexpensive approach to "fill all transactions of all blocks" and "prevent any real transaction from occurring" via a "Sapling Wood-Chipper" attack.
{
"versions": [
{
"introduced": "2.0.0"
},
{
"last_affected": "2.0.4"
},
{
"introduced": "0"
},
{
"last_affected": "2.0.5-rc1"
}
]
}