rclone serve s3 versions 1.75.0 up to but not including 1.75.2 contain an integer overflow vulnerability in multipart reorder-memory accounting. This flaw allows attackers to bypass the configured buffer memory limit by opening two concurrent current-part PUT requests with large declared lengths, causing the signed int64 counter to wrap and retain out-of-order parts in memory. This can exhaust the host's memory resources. The issue is fixed in version 1.75.2.