Versions of ecstatic prior to 1.4.0 are affected by a denial of service vulnerability when certain input strings are sent via the Last-Modified or If-Modified-Since headers.
Parsing certain inputs with new Date() or Date.parse() cases v8 to crash. As ecstatic passes the value of the affected headers into one of these functions, sending certain inputs via one of the headers will cause the server to crash.
Update to version 1.4.0 or later.
{
    "nvd_published_at": null,
    "github_reviewed_at": "2020-06-16T21:58:32Z",
    "cwe_ids": [
        "CWE-400"
    ],
    "severity": "HIGH",
    "github_reviewed": true
}