CVE-2026-45401

# Server-Side Request Forgery (SSRF) Bypass via HTTP Redirect Following in Web-Fetch, Image-Load, and Chat-Completion Endpoints ## Summary The `validate_url()` function in `backend/open_webui/retrieval/web/utils.py` only validates the *initial* URL submitted by the caller. The HTTP clients used downstream (sync `requests`, async `aiohttp`, langchain's `WebBaseLoader`) follow HTTP 3xx redirects by default and do **not** re-validate the redirect target against the private-IP / metadata-IP block list. Any authenticated user can therefore submit a public URL that 302-redirects to an internal address (e.g. `127.0.0.1`, `169.254.169.254`, RFC1918) and read the internal response body via the `/api/v1/retrieval/process/web` endpoint, the `/api/v1/images/...` endpoints, the `/api/chat/completions` endpoint with an `image_url` content part, and any other route that calls these helpers. ## Affected code paths The bypass exists across multiple call sites; each independently follows redirects without re-validation. ### Path 1 — sync `_scrape` via `SafeWebBaseLoader` `backend/open_webui/retrieval/web/utils.py` — `SafeWebBaseLoader` inherits from `langchain_community.document_loaders.WebBaseLoader`. The parent's `_scrape()` calls `self.session.get(url, **self.requests_kwargs)`. `requests_kwargs` only sets `timeout`; `allow_redirects=False` is **not** passed, so `requests.Session.get()` follows redirects with the default `allow_redirects=True`. `validate_url()` is invoked once on the original URL only. ### Path 2 — async `_fetch` (aiohttp) `backend/open_webui/retrieval/web/utils.py` — `_fetch()` previously inherited the aiohttp default `allow_redirects=True`. As of HEAD this path is fixed (`allow_redirects=False`). Listed for completeness. ### Path 3 — `get_content_from_url` (sync `requests.get`) `backend/open_webui/retrieval/utils.py` — `response = requests.get(url, stream=True, timeout=30)`. No `allow_redirects=False`. Reached via `/api/v1/retrieval/process/web` (file i