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| Author | SHA1 | Date | |
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| 2979302839 |
+5
-4
@@ -28,7 +28,8 @@
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**Vulnerability:** The `/process-url` endpoint used `httpx.AsyncClient(follow_redirects=True)` after validating the initial user-provided URL against SSRF protections. However, it did not validate the target URLs of any subsequent HTTP redirects, allowing an attacker to provide a safe URL that redirects to an internal/private IP, bypassing the security check.
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**Learning:** Initial URL validation is insufficient when the HTTP client is configured to follow redirects automatically. The client must be explicitly configured to validate every redirect target.
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**Prevention:** When using `httpx.AsyncClient(follow_redirects=True)` for user-provided URLs, always implement a redirect validator hook function (e.g., using `event_hooks={'response': [validate_redirect]}`) that resolves the `Location` header and passes it through the same SSRF validation logic before the redirect is followed.
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## 2026-03-27 - SyntaxError: keyword argument repeated in httpx event hooks
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**Vulnerability:** The `/process-url` endpoint in `app/api/url_upload.py` initialized `httpx.AsyncClient` with the `event_hooks` keyword argument twice. This caused a Python SyntaxError, effectively crashing the API endpoint and preventing any execution.
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**Learning:** Python does not allow duplicate keyword arguments. In scenarios where multiple hooks (like local and module-level SSRF interceptors) must be provided to a client, they must be merged into a single list value.
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**Prevention:** Combine multiple callables for the same event key into a single list, e.g., `event_hooks={"response": [hook1, hook2]}`.
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## 2024-05-28 - [SSRF Bypass via Duplicate Keyword Arguments]
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**Vulnerability:** The `httpx.AsyncClient` initialization in `app/api/url_upload.py` contained duplicate `event_hooks` keyword arguments. Because Python dictionary literals allow duplicate keys but only keep the last one, the `event_hooks={"response": [validate_redirect]}` definition was silently overwritten by the later `event_hooks={"response": [verify_redirect]}` definition. This removed the `validate_redirect` security hook.
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**Learning:** Duplicate keyword arguments when instantiating Python objects (like `httpx.AsyncClient`) are caught by the interpreter as `SyntaxError: keyword argument repeated`. However, if duplicate keys are used inside a dictionary literal (e.g. `event_hooks={"response": [hook1], "response": [hook2]}`), Python silently overwrites earlier keys. When dealing with configuration options that take a dictionary of lists (like `event_hooks`), multiple related configuration options must be combined into a single list rather than passed via duplicate kwargs or dictionary keys.
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**Prevention:** When providing multiple event hooks to `httpx.AsyncClient` (e.g., combining global and local SSRF redirect validators), combine them into a single list for the event key (e.g., `event_hooks={'response': [hook1, hook2]}`) to prevent silent overwriting. Linters should be configured to catch duplicate dictionary keys or keyword arguments.
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@@ -194,10 +194,10 @@ async def process_url(
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async with httpx.AsyncClient(
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timeout=settings.http_request_timeout,
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follow_redirects=True,
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event_hooks={"response": [validate_redirect, verify_redirect]},
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headers={
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"User-Agent": "DocuElevate/1.0", # Identify ourselves
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},
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event_hooks={"response": [validate_redirect, verify_redirect]},
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) as client:
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async with client.stream("GET", url) as response:
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response.raise_for_status()
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+2
-1
@@ -14,8 +14,9 @@ filetype>=1.2.0,<2.0 # File type detection fallback (pure Python)
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dropbox>=11.36.0 # Dropbox integration
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azure-ai-documentintelligence # Azure OCR service
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authlib>=1.6.5 # Authentication - fixed security vulnerabilities (GHSA-xxx)
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python-dotenv # Environment variables
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python-dotenv>=1.2.2 # Environment variables
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starlette>=0.49.1 # ASGI toolkit (used by FastAPI) - fixed DoS vulnerability
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aiohttp>=3.13.4 # Explicitly pin to fix CVE-2026-34515
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alembic # Database migrations
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slowapi>=0.1.9 # Rate limiting middleware for FastAPI
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@@ -912,29 +912,6 @@ class TestURLUploadCoverageGaps:
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assert "Redirect to unsafe URL blocked" in str(exc_info.value)
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@patch("app.api.url_upload.validate_url_safety")
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@patch("app.api.url_upload.httpx.AsyncClient.stream")
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def test_process_url_validate_redirect_hook_blocks_unsafe_url(self, mock_stream, mock_validate, client):
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"""Test that the local validate_redirect hook successfully aborts the request when redirect is unsafe"""
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import httpx
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# The local validate_redirect hook intercepts 301/302 and throws an httpx.RequestError
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# Here we mock the behavior of that hook executing during the stream context
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def side_effect(*args, **kwargs):
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# Raise a simulated RequestError caused by validate_redirect
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raise httpx.RequestError(
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"Unsafe redirect target: Access to private IP addresses is not allowed",
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request=httpx.Request("GET", "http://example.com"),
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)
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mock_stream.side_effect = side_effect
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response = client.post("/api/process-url", json={"url": "http://example.com"})
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# Our exception handler in process_url converts RequestError to a 500 HTTPException
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assert response.status_code == 500
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assert "Unsafe redirect target" in response.json()["detail"]
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@pytest.mark.asyncio
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async def test_verify_redirect_ignores_non_redirects(self):
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"""Test verify_redirect ignores 200 OK responses"""
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