CVE-2026-59223: Open WebUI `WEB_FETCH_FILTER_LIST` Host Allow/block Filter Bypassable Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qg3f-8x3j-ggf2",
  "modified" : "2026-07-24T20:49:40Z",
  "published" : "2026-07-24T20:49:40Z",
  "aliases" : [ "CVE-2026-59223" ],
  "summary" : "Open WebUI: `WEB_FETCH_FILTER_LIST` host allow/block filter bypassable via URL path and non-label-boundary matching",
  "details" : "## Summary\n\nThe 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.\n\n## Details\n\n`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:\n\n- **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.\n- **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`.\n- **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`.\n\n## Impact\n\nAn authenticated user able to trigger a server-side web fetch can reach hosts the administrator intended to block with `WEB_FETCH_FILTER_LIST`.\n\nOpen 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`, active whenever `ENABLE_RAG_LOCAL_WEB_FETCH` is off, the default). That guard is unaffected by this issue and continues to block loopback, RFC1918 and link-local addresses, including the `169.254.169.254` cloud-metadata endpoint. This bypass therefore does **not** grant access to those internal targets. What it defeats is the administrator's ability to block specific **publicly-resolvable** hosts (internal services reachable from the server over a public IP, e.g. split-horizon DNS or internal PaaS endpoints) and to enforce an allowlist. Fetched content is returned to the requester, so for hosts reachable from the server's network position this is a read/content-disclosure SSRF against the admin-blocked host.\n\n## Patch\n\nMatching is now performed on the parsed hostname using DNS label boundaries. A dedicated `is_host_allowed(host, ...)` matches an entry only when host and entry are equal or the entry is a parent domain (`host == entry or host.endswith('.' + entry)`), so `corp.com` matches `api.corp.com` but not `evilcorp.com`, and IP entries match only the identical address. Both web-fetch call sites pass the parsed hostname rather than the full URL. The generic `is_string_allowed` is retained unchanged for unrelated non-host filters.\n\n## Credit\n\nReported by @addcontent.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "open-webui"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.10.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/security/advisories/GHSA-qg3f-8x3j-ggf2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59223"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/pull/25949"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/commit/087878ce848a4d828012068b5997dac480f43656"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/open-webui/open-webui"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/releases/tag/v0.10.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-693" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-24T20:49:40Z",
    "nvd_published_at" : "2026-07-09T17:17:03Z"
  }
}