GHSA-QG3F-8X3J-GGF2
Vulnerability from github – Published: 2026-07-24 20:49 – Updated: 2026-07-24 20:49Summary
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.comonly 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.comrejected the legitimatehttps://api.company.com/statusand admittedhttps://attacker.example/path/company.com. - Non-label-boundary matching at the hostname-shaped call site (
retrieval/web/main.py):endswith('corp.com')also matchedevilcorp.com, and10.0.0.1matched110.0.0.1.
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, 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.
Patch
Matching 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.
Credit
Reported by @addcontent.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "open-webui"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.10.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-59223"
],
"database_specific": {
"cwe_ids": [
"CWE-693"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-24T20:49:40Z",
"nvd_published_at": "2026-07-09T17:17:03Z",
"severity": "MODERATE"
},
"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(\u0027corp.com\u0027)` 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\u0027s 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\u0027s 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\u0027s 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(\u0027.\u0027 + 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.",
"id": "GHSA-qg3f-8x3j-ggf2",
"modified": "2026-07-24T20:49:40Z",
"published": "2026-07-24T20:49:40Z",
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Open WebUI: `WEB_FETCH_FILTER_LIST` host allow/block filter bypassable via URL path and non-label-boundary matching"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.