CVE-2026-48824

### Summary The fix for GHSA-fpxj-m5q8-fphw (CVE-2026-45710, "Mailpit: Set a default 50MB p/m limit to prevent DoS via unlimited SMTP DATA and /api/v1/send body sizes") wrapped only `POST /api/v1/send` with `http.MaxBytesReader`. The four other Mailpit JSON-body API endpoints `PUT /api/v1/messages` (SetReadStatus), `DELETE /api/v1/messages` (DeleteMessages), `PUT /api/v1/tags` (SetMessageTags), and `POST /api/v1/message/{id}/release` (ReleaseMessage) still call `json.NewDecoder(r.Body)` directly with no body-size cap and remain reachable unauthenticated in the default `docker run axllent/mailpit:latest` deploy. An unauthenticated remote attacker can post a multi-million-element `IDs` slice and drive RSS from ~25 MiB baseline to ~450 MiB per 16 MB request body. Repeating across multiple connections accumulates the same per-request amplification per process. ### Affected versions - Mailpit at HEAD `67a7ca83ff759082d2b86dda07eb5bb3dad404e0` (v1.30.0, 2026-05-14). - All versions `<= v1.30.0` (the release that shipped the GHSA-fpxj fix). Versions `< v1.30.0` are vulnerable to the original GHSA-fpxj on `/api/v1/send`; version `v1.30.0` carries the sibling-endpoint gap described here. ### Privilege required None in default deploy (no `--ui-auth`, no `--smtp-auth`). The four endpoints share the same `middleWareFunc` wrapper as the original GHSA-fpxj target, so the same default-no-auth threat model applies. With `--ui-auth=user:pass` configured, the same primitive is post-auth — still useful since UI-auth Mailpit deployments commonly run on internal ops subnets where one stolen UI credential pivots into an RSS-exhaustion vector against the same host. ### The incomplete fix Commit `136bdde` ("Security: Set a default 50MB p/m limit to prevent DoS via unlimited SMTP DATA and /api/v1/send body sizes (GHSA-fpxj-m5q8-fphw)", 2026-05-12) added the `MaxBytesReader` wrap in exactly one place: ```go // server/apiv1/send.go:45-48 if config.MaxMessageSize > 0 { r.Body = ht