diff --git a/docs/ADMIN_API.md b/docs/ADMIN_API.md
index d5a7fe2478..c2f3cf705e 100644
--- a/docs/ADMIN_API.md
+++ b/docs/ADMIN_API.md
@@ -9,6 +9,8 @@ To enable the admin API, and manage namespaces, two extra flags need to be passe
 - `--admin-listen-addr <addr>:<port>`: the address and port on which the admin API should listen. It must be different from the user API listen address (which defaults to port 8080).
 - `--enable-namespaces`: enable namespaces for the instance. By default namespaces are disabled.
 
+**The admin API has no authentication unless you also set `--admin-auth-key <key>` (or the `LIBSQL_ADMIN_AUTH_KEY` environment variable).** Without it, anyone who can reach `--admin-listen-addr` can create, delete, and fork any namespace, and can rewrite a namespace's own config, including its `jwt_key` (which controls who can authenticate to that namespace's user-facing API) and `heartbeat_url`/`dump_url` (both of which cause the server to make an outbound request to a URL in the request body). Always set `--admin-auth-key` when `--admin-listen-addr` is reachable from anywhere other than a fully trusted local process, and prefer binding it to a loopback or private-network address rather than `0.0.0.0`.
+
 ## Routes
 
 ```HTTP
diff --git a/docs/DOCKER.md b/docs/DOCKER.md
index 17a1ade208..5492ff80d1 100644
--- a/docs/DOCKER.md
+++ b/docs/DOCKER.md
@@ -77,6 +77,14 @@ the Ed25519 public key in URL-safe base64.
 
 You can also pass the key directly in the env variable SQLD_AUTH_JWT_KEY.
 
+### `LIBSQL_ADMIN_AUTH_KEY`
+
+Auth key for the admin API (`SQLD_ADMIN_LISTEN_ADDR`). The admin API has no
+authentication at all unless this is set, and it manages every namespace on
+the instance (create/delete/fork, and per-namespace config including
+`jwt_key`). If you set `SQLD_ADMIN_LISTEN_ADDR` to anything reachable outside
+a fully trusted local process, set this too. See `docs/ADMIN_API.md`.
+
 ## Environment variables
 
 ### `SQLD_NODE`