CVE-2026-33637 is a low-severity server-side request forgery (SSRF) vulnerability in faraday (rubygems), affecting versions >= 2.0.0, <= 2.14.1. It is fixed in 2.14.2.
Summary Faraday::Connection#buildexclusiveurl still allows protocol-relative host override when the request target is provided as a URI object instead of a String. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and can redirect a request built from a fixed-base Faraday::Connection to an attacker-controlled host while preserving connection-scoped headers such as Authorization. Affected Component Repository File(s)/Endpoint(s): lib/faraday/connection.rb lib/faraday/request.rb spec/faraday/connectionspec.rb spec/faraday/requestspec.rb Function(s): Faraday::Connection#buildexclusiveurl Faraday::Connection#runrequest Faraday::Request#url Faraday::Request#toenv Version(s) Tested: Faraday 2.14.1 repository HEAD a01039c948d3e9e41e03d152aed7244f0fb4d5ca Attacker Profile Who: A remote user who can influence a per-request target/path in an application that uses a fixed-base Faraday connection Access Required: Ability to supply data that the application converts to URI.parse(...) and passes to conn.get(...), conn.post(...), or req.url(...) Capability: Control over a protocol-relative URI such as URI("//evil.example/pwn") Steps to Reproduce Use the current repository checkout and load Faraday from lib/. Build a fixed-base connection and provide a protocol-relative URI object to req.url. Observe that the request is actually sent to the attacker-controlled host instead of the configured base host. Observe that the connection-scoped Authorization header remains attached to the off-host request. Verification Evidence Environment: macOS, Ruby from local environment, Faraday 2.14.1, faraday-nethttp, local WEBrick listener on 127.0.0.1:4567, HEAD a01039c948d3e9e41e03d152aed7244f0fb4d5ca Commands executed: PoC code (inline): Exit code: 0 stdout (relevant excerpt): stderr (relevant excerpt): Artifacts: none Additional External Confirmation The issue was also independently reproduced against a public HTTP collector on Faraday 2.14.1 using the default nethttp adapter: This external confirmation shows the request is not only misbuilt in memory, but is actually dispatched off-host by a real adapter under normal usage. Supporting Materials Existing advisory for the original string-based issue: GHSA-33mh-2634-fwr2 Existing CVE for the original string-based issue: CVE-2026-25765 Existing regression tests for the string-only fix: spec/faraday/connectionspec.rb:314-345 Existing test proving supported URI request input: spec/faraday/requestspec.rb:26-31 Impact The direct consequence is off-host request forgery from code paths that believe they are constrained to a fixed base URL. If the connection carries default headers or query parameters, those values are forwarded to the attacker-selected host.
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.
rubygems
faraday (>= 2.0.0, <= 2.14.1)faraday → 2.14.2 (rubygems)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.
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Upgrade faraday to 2.14.2 or later to resolve this vulnerability.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-33637 is a low-severity server-side request forgery (SSRF) vulnerability in faraday (rubygems), affecting versions >= 2.0.0, <= 2.14.1. It is fixed in 2.14.2. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
faraday (rubygems) versions >= 2.0.0, <= 2.14.1 is affected.
Yes. CVE-2026-33637 is fixed in 2.14.2. Upgrade to this version or later.
Whether CVE-2026-33637 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
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.
Upgrade faraday to 2.14.2 or later.