In Twisted Web before 20.3.0, there was an HTTP request splitting vulnerability. When presented with two content-length headers, it ignored the first header. When the second content-length value was set to zero, the request body was interpreted as a pipelined request.
{
"github_reviewed": true,
"cwe_ids": [
"CWE-20",
"CWE-444"
],
"github_reviewed_at": "2020-03-31T15:28:25Z",
"nvd_published_at": "2020-03-12T13:15:00Z",
"severity": "CRITICAL"
}