Remote unauthenticated attackers can overwrite arbitrary server files with attacker-controllable data. The data that the attacker can control is not entirely arbitrary. h2o writes a CSV/XLS/etc file to disk, so the attacker data is wrapped in quotations and starts with "C1", if they're exporting as CSV.
{ "nvd_published_at": "2023-12-14T13:15:55Z", "cwe_ids": [ "CWE-610", "CWE-73" ], "severity": "CRITICAL", "github_reviewed": true, "github_reviewed_at": "2023-12-15T03:12:43Z" }