Improve security

README.md

@@ -82,10 +82,12 @@ Create a user, then log in through the UI at `http://localhost:5173`:
 
 ```sh
 curl -X POST -H "Content-Type: application/json" \
-  -d '{"name": "mace", "email": "you@example.com", "password": "secret"}' \
+  -d '{"name": "mace", "email": "you@example.com", "password": "secret1"}' \
   http://localhost:8001/api/v1/user/create
 ```
 
+Passwords must be at least 6 characters.
+
 ### Useful commands during development
 
 ```sh
@@ -110,6 +112,30 @@ docker exec -it rss-postgres psql -d rss -U admin
 
 ---
 
+## Security notes
+
+- **Sessions**: login returns a JWT (`token` header) valid for 24 hours. Logging out
+  (`POST /api/v1/auth/logout`, requires the current token) bumps the user's
+  `token_version`, which immediately invalidates *all* outstanding tokens for that
+  account — there's no per-session revocation, so logging out on one device logs out
+  every device.
+- **Login rate limiting**: `POST /api/v1/auth/login` is limited to a burst of 5 requests
+  per IP, replenishing one every 2 seconds (`actix-governor`).
+- **Outbound fetches**: feed syncs and the article-reader endpoint only fetch
+  `http`/`https` URLs that resolve to public IP addresses (no loopback/private/
+  link-local, e.g. `127.0.0.1` or the `169.254.169.254` cloud metadata address).
+  Redirects are followed (up to 5 hops), but each redirect target is checked against the
+  same rules before being fetched, so a redirect can't be used to reach an internal
+  address.
+- **Stored feed content**: `<img>` tags from synced feed content are sanitized
+  (`ammonia`) down to `src`/`alt`/`title` before being stored, since they're later
+  rendered with `v-html` in the frontend.
+- **If `JWT_SECRET` or `POSTGRES_PASSWORD` are ever leaked** (e.g. committed to git),
+  rotate them in `.env` and restart the backend — rotating `JWT_SECRET` invalidates every
+  outstanding token as a side effect.
+
+---
+
 ## Production setup (Docker)
 
 The whole stack — Postgres, backend, and frontend — runs via Docker Compose. The frontend is built as a static Vue bundle and served by nginx, which also reverse-proxies `/api/` to the backend container.