{"affected":[{"package":{"ecosystem":"Hex","name":"tidewave","purl":"pkg:hex/tidewave"},"ranges":[{"events":[{"introduced":"0.8.0"},{"fixed":"0.9.2"}],"type":"SEMVER"}],"versions":["0.8.0","0.8.1","0.8.2","0.8.3","0.8.4","0.9.0","0.9.1"]},{"ranges":[{"events":[{"introduced":"f78352b56d19cd4ae49999aa385011cef73e8b93"},{"fixed":"80159536f752dc4d34797934d1516f29cea12b50"}],"repo":"https://github.com/tidewave-ai/tidewave_phoenix","type":"GIT"}]}],"aliases":["CVE-2026-109823"],"credits":[{"name":"Neil Berkman","type":"FINDER"},{"name":"Neil Berkman","type":"REPORTER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}],"database_specific":{"capec_ids":["CAPEC-170"],"cpe_ids":["cpe:2.3:a:tidewave-ai:tidewave:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-497"]},"details":"## Summary\n\nAn attacker can read the name of filesystem paths of your application present via Tidewave configuration via /tidewave/connect or via the rendered toolbar.\n\nNeither response checks the `Host` header. A web page that rebinds its own domain to the loopback address can therefore read the tag with a same-origin request, which carries no `Origin` header. The paths usually reveal the local username and the project layout.\n\nThis issue affects tidewave: from 0.8.0 before 0.9.2.\n\n## Details\n\n**1. Data collection.** `Tidewave.tidewave_config_meta/1` builds a map with `root` (`Tidewave.MCP.root()`), `framework.app_paths` (`Mix.Project.deps_paths()`), `wsl_distro`, and `host_path`. It HTML-escapes the JSON encoding of the map into `<meta name=\"tidewave:config\">`.\n\n**2. Exposure.** `Tidewave.Router.control_html/1` serves the tag on `GET /tidewave/connect`. For all other routes, `Tidewave.call/2` registers a `before_send` callback that injects the tag into every `text/html` response when `toolbar: true`.\n\n**3. Read access.** `check_origin/2` accepts any request without an `Origin` header, and no code validates `Host`. After DNS rebinding, the browser sends a same-origin `GET` from a loopback peer.\n\n## Proof of concept\n\n1. Run a Phoenix or Plug application with `plug Tidewave` on `127.0.0.1:4001`.\n2. From a loopback peer, send `GET /tidewave/connect` with `Host: attacker.example:4001` and `Sec-Fetch-Site: same-origin`, and no `Origin` header. This is the request a DNS-rebound page makes.\n3. The server answers `200 OK`. The `tidewave:config` meta tag contains the absolute project root and the dependency paths.\n4. Send the same request to any HTML route of the application. The injected toolbar tag contains the same data.\n\n## Impact\n\nA malicious web page that a developer visits while the Phoenix development server runs can learn the developer's username, project location, and dependency layout on disk. This information helps an attacker prepare further attacks against the machine.","id":"EEF-CVE-2026-109823","modified":"2026-10-27T15:47:37.307672Z","published":"2026-10-27T15:47:36.862Z","references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-109823.html"},{"type":"WEB","url":"https://github.com/tidewave-ai/tidewave_phoenix/commit/f78352b56d19cd4ae49999aa385011cef73e8b93"},{"type":"FIX","url":"https://github.com/tidewave-ai/tidewave_phoenix/commit/80159536f752dc4d34797934d1516f29cea12b50"},{"type":"PACKAGE","url":"https://hex.pm/packages/tidewave"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","type":"CVSS_V4"}],"summary":"Host filesystem path disclosure via DNS rebinding","upstream":[]}