Open WebUI: WEB_FETCH_FILTER_LIST host allow/block filter bypassable via URL path and non-label-boundary matching

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2026-59223: 0.38% estimated exploitation activity in the next 30 days; percentile 32.38 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The administrator-configured WEBFETCHFILTERLIST (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 isstringallowed (backend/openwebui/utils/misc.py) matches with str.endswith(...), and the primary web-fetch call site (backend/openwebui/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…

Published by the source

24 Jul 2026, 20:49 UTC

Last modified by the source

4 Aug 2026, 14:40 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-qg3f-8x3j-ggf2

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-qg3f-8x3j-ggf2

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# Patch Next advisory brief: CVE-2026-59223

Advisory: Open WebUI: `WEB_FETCH_FILTER_LIST` host allow/block filter bypassable via URL path and non-label-boundary matching
IDs: CVE-2026-59223, GHSA-qg3f-8x3j-ggf2
Record: https://patchnext.com/advisories/cve-2026-59223 (revision 2, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.10.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected < 0.10.0; fixed in 0.10.0

## Suggested inspection (read-only)
- `python -m pip show open-webui`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on open-webui.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-qg3f-8x3j-ggf2 (OSV record GHSA-qg3f-8x3j-ggf2 lists affected ranges: PyPI open-webui >=0 <0.10.0 (fixed))
- Verified: https://github.com/advisories/GHSA-qg3f-8x3j-ggf2 (GitHub-reviewed advisory GHSA-qg3f-8x3j-ggf2 lists affected ranges: PyPI open-webui >=0 <0.10.0)

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