CVE-2026-25765

Description

Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Prior to 2.14.1, 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). This vulnerability is fixed in 2.14.1.

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

References

• https://github.com/lostisland/faraday/security/advisories/GHSA-33mh-2634-fwr2
• https://nvd.nist.gov/vuln/detail/CVE-2026-25765
• https://github.com/lostisland/faraday/pull/1569
• https://github.com/lostisland/faraday/commit/a6d3a3a0bf59c2ab307d0abd91bc126aef5561bc
• https://github.com/lostisland/faraday
• https://github.com/lostisland/faraday/releases/tag/v1.10.5
• https://github.com/lostisland/faraday/releases/tag/v2.14.1
• https://github.com/rubysec/ruby-advisory-db/blob/master/gems/faraday/CVE-2026-25765.yml
• https://www.rfc-editor.org/rfc/rfc3986#section-5.2.2
• https://www.rfc-editor.org/rfc/rfc3986#section-5.4
• https://security-tracker.debian.org/tracker/CVE-2026-25765