Affected: open-webui

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. Prior to 0.10.0, WEB_FETCH_FILTER_LIST matching compared configured host entries against URL strings and non-label-boundary suffixes, allowing path-based blocklist bypasses such as !internal.example.com in a URL path and sibling-domain matches that did not reflect the intended hostname policy. This issue is fixed in version 0.10.0.

Affected: PyPI: open-webui

## Summary

The administrator-configured `WEB_FETCH_FILTER_LIST` (the allow/block list applied to server-side web fetches: RAG URL ingestion, URL-to-markdown, web-search content fetch) matches hostnames incorrectly, so the filter can be bypassed.

## Details

`is_string_allowed` (`backend/open_webui/utils/misc.py`) matches with `str.endswith(...)`, and the primary web-fetch call site (`backend/open_webui/retrieval/web/utils.py`) called it with the **full URL string**, not the hostname:

- **Blocklist bypass via path.** A blocklist entry `!internal.example.com` only matches a URL that *ends with* that string. Any URL with a path (`https://internal.example.com/x`) ends with `/x`, so the entry never matches and the fetch proceeds. The blocklist effectively only stopped path-less URLs. - **Allowlist false-reject and bypass.** An allowlist `company.com` rejected the legitimate `https://api.company.com/status` and admitted `https://attacker.example/path/company.com`. - **Non-label-boundary matching** at the hostname-shaped call site (`retrieval/web/main.py`): `endswith('corp.com')` also matched `evilcorp.com`, and `10.0.0.1` matched `110.0.0.1`.

## Impact

An authenticated user able to trigger a server-side web fetch can reach hosts the administrator intended to block with `WEB_FETCH_FILTER_LIST`.

Open WebUI's primary SSRF protection is a separate, always-on guard that rejects any URL resolving to a non-global IP (`validate_url` and the connection-layer `_ssrf_safe_new_conn`, ac…