docs: add sections about new WEBHOOK_ALLOWED_ORIGINS env var

README.md

@@ -109,6 +109,7 @@ Zerobyte can be customized using environment variables. Below are the available
 | `TZ`                  | Timezone for the container (e.g., `Europe/Zurich`). **Crucial for accurate backup scheduling.**                                           | `UTC`                  |
 | `TRUST_PROXY`         | When `true`, trust an existing `X-Forwarded-For` header from your reverse proxy. Leave `false` for direct deployments.                    | `false`                |
 | `TRUSTED_ORIGINS`     | Comma-separated list of extra trusted origins for CORS (e.g., `http://localhost:3000,http://example.com`).                                | (none)                 |
+| `WEBHOOK_ALLOWED_ORIGINS` | Comma-separated list of HTTP origins allowed for backup webhooks and outbound HTTP notification destinations.                          | (none)                 |
 | `LOG_LEVEL`           | Logging verbosity. Options: `debug`, `info`, `warn`, `error`.                                                                             | `info`                 |
 | `SERVER_IDLE_TIMEOUT` | Idle timeout for the server in seconds.                                                                                                   | `60`                   |
 | `RCLONE_CONFIG_DIR`   | Path to the directory containing `rclone.conf` inside the container. Change this if running as a non-root user.                           | `/root/.config/rclone` |

apps/docs/content/docs/configuration.mdx

@@ -37,6 +37,7 @@ Zerobyte is configured through environment variables and Docker Compose settings
 | `RESTIC_HOSTNAME` | Hostname used by Restic when creating snapshots. Automatically detected if a custom hostname is set in Docker. | `zerobyte` |
 | `TRUST_PROXY` | Set to `true` to trust `X-Forwarded-For` headers from a reverse proxy. | `false` |
 | `TRUSTED_ORIGINS` | Comma-separated list of additional trusted origins for CORS. | (none) |
+| `WEBHOOK_ALLOWED_ORIGINS` | Comma-separated list of HTTP origins allowed for backup webhooks and outbound HTTP notification destinations. | (none) |
 | `LOG_LEVEL` | Logging verbosity: `debug`, `info`, `warn`, `error`. | `info` |
 | `SERVER_IDLE_TIMEOUT` | Server idle timeout in seconds. | `60` |
 | `RCLONE_CONFIG_DIR` | Path to the rclone config directory inside the container. | `/root/.config/rclone` |

apps/docs/content/docs/guides/notifications.mdx

@@ -36,6 +36,10 @@ You create destinations under **Notifications**. You route them per backup sched
 | `Generic Webhook` | Arbitrary HTTP endpoints and automation systems | URL, method, headers, content type, optional JSON template keys |
 | `Custom (Shoutrrr URL)` | Power users or services not exposed by the built-in forms | Raw Shoutrrr URL |
 
+<Callout type="warn">
+  Outbound HTTP notification destinations must use an origin listed in `WEBHOOK_ALLOWED_ORIGINS`. This applies to Generic Webhook, Gotify, self-hosted ntfy servers, and Custom Shoutrrr URLs that resolve to a custom HTTP endpoint.
+</Callout>
+
 ## Which type should I use?
 
 - Choose **Email** when you already trust an SMTP relay and want easy fan-out to multiple recipients.
@@ -163,6 +167,10 @@ Each assignment is independent. One schedule can send failures to Email, warning
     - `App Token`
     - `Priority` from `0` to `10`
     - `Path` (optional)
+
+    **Notes**
+
+    - Add the Gotify server origin, such as `https://gotify.example.com`, to `WEBHOOK_ALLOWED_ORIGINS`.
   </Tab>
 
   <Tab value="ntfy">
@@ -178,6 +186,8 @@ Each assignment is independent. One schedule can send failures to Email, warning
 
     **Notes**
 
+    - Leave `Server URL` empty to use `ntfy.sh`.
+    - Add self-hosted ntfy origins, such as `https://ntfy.example.com`, to `WEBHOOK_ALLOWED_ORIGINS`.
     - If you set an access token, it takes precedence over username and password.
     - Priority values are `max`, `high`, `default`, `low`, and `min`.
 
@@ -236,6 +246,7 @@ Each assignment is independent. One schedule can send failures to Email, warning
 
     **Notes**
 
+    - Add the webhook origin, such as `https://hooks.example.com`, to `WEBHOOK_ALLOWED_ORIGINS`.
     - Headers are entered one per line as `Key: Value`.
     - With JSON mode enabled, Zerobyte sends a body shaped like `{titleKey: "...", messageKey: "..."}`.
     - With JSON mode disabled, the request body is plain notification text.
@@ -261,6 +272,8 @@ Each assignment is independent. One schedule can send failures to Email, warning
 
     See the [Shoutrrr documentation](https://shoutrrr.nickfedor.com/services/overview) for the supported URL formats and service-specific options.
 
+    If the Shoutrrr URL targets a custom HTTP endpoint, add that endpoint origin to `WEBHOOK_ALLOWED_ORIGINS`.
+
     **Fields**
 
     - `Shoutrrr URL`