CVE-2026-54617: Launchserver api Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5g75-477j-2c2f",
  "modified" : "2026-07-02T20:49:18Z",
  "published" : "2026-07-02T20:49:18Z",
  "aliases" : [ "CVE-2026-54617" ],
  "summary" : "LaunchServer FileServerHandler has an unauthenticated path traversal issue",
  "details" : "### Summary\nAn unauthenticated path traversal in the LaunchServer HTTP file server (`FileServerHandler`) lets any remote actor read **any file** readable by the LaunchServer process (e.g. `../../../../etc/passwd`). This is a generic arbitrary-file-read primitive, so the fix must address the traversal itself, not any specific file.\n\nThe readable files include the server's own secrets, which turns this from information disclosure into full compromise: the ECDSA private key that signs access JWTs (`.keys/ecdsa_id`), the refresh-token salt (`.keys/legacySalt`), and `LaunchServer.json` (database credentials). With the signing key an attacker mints a valid access token for any account, including admins. That is a full authentication bypass. Pre-auth, default config, port 9274.\n\n**Affected:** GravitLauncher LaunchServer ≤ 5.7.11 (the LaunchServer application; the published `pro.gravit.launcher:*-api` Maven artifacts do not contain the vulnerable code).\n\n### Details\nIn `FileServerHandler.channelRead0`:\n\n```java\npath = Paths.get(IOHelper.getPathFromUrlFragment(uri)).normalize().toString().substring(1); // line 194\nFile file = base.resolve(path).toFile();                                                     // line 200 - no second normalize()\n```\n\n`substring(1)` blindly strips a leading slash, assuming the request-target always starts with `/`. Netty's `HttpServerCodec` accepts a request-target **without** a leading slash verbatim (`decoderResult().isSuccess() == true`). For such a target, `normalize()` cannot collapse the leading `..`, `substring(1)` turns `../` into `./` (leaving the remaining `..`), and `base.resolve(path)`, which is not re-normalized, resolves **outside** `updatesDir`.\n\n`file.isHidden()` (line 201) is checked only on the final path component, so targets that don't start with a dot (`ecdsa_id`, `rsa_id`, `legacySalt`, `LaunchServer.json`) are served even with `showHiddenFiles=false`.\n\nThe file server is enabled by default (`netty.fileServerEnabled=true`) and bound to `0.0.0.0:9274`. No auth handler precedes `FileServerHandler`; `WebSocketServerProtocolHandler(\"/api\")` forwards non-WebSocket / non-`/api` requests down to it, so the attack is a plain HTTP GET (no WebSocket).\n\n### PoC\nReproduced on a from-source build of v5.7.11 (Netty 4.2.12).\n**Must use a raw socket.** curl/browsers/HTTP libraries normalize the path and prepend `/`, hitting the safe branch (false \"not reproducible\").\n\n```\nprintf 'GET ../../.keys/ecdsa_id HTTP/1.1\\r\\nHost: x\\r\\n\\r\\n' | nc <host> 9274\n```\n\nReturns the raw ECDSA private-key bytes. Same for `../../.keys/rsa_id`, `../../.keys/legacySalt`, `../../LaunchServer.json`. `%2e%2e/...` (no leading slash) also works. Depth-robust arbitrary read: `../../../../../../etc/passwd`.\nControl (confirms the root cause): `GET /../../.keys/ecdsa_id` (WITH leading slash) → 404. Only the no-leading-slash form escapes.\n\n### Impact\nUnauthenticated remote read of any file the process can access. What that exposes:\n- `.keys/ecdsa_id`: the key that signs access JWTs. With it, an attacker mints a valid token for any account, including admins, so this is a full authentication bypass.\n- `.keys/legacySalt`: lets an attacker forge refresh tokens.\n- `LaunchServer.json`: database credentials.\n- Any other file readable by the process (config, logs, system files).\n\nDeployment note: a normalizing L7 reverse proxy (stock nginx `location / { proxy_pass ...; }`) rejects the no-leading-slash request (400) and collapses leading-slash traversal, blocking the primary vector. But the default bind is `0.0.0.0:9274`, so protection relies on firewalling the backend port; L4/TCP proxies (HAProxy TCP, nginx `stream`, CF Spectrum) and direct exposure remain exploitable.\n\n### Suggested fix\n1. Re-`normalize()` after `base.resolve(path)` and verify `resolved.startsWith(base)`.\n2. Reject request-targets that don't start with `/` (400).\n3. Default-bind to `127.0.0.1`; store `.keys` outside `updatesDir`.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "pro.gravit.launcher:launchserver-api"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "5.7.11"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/GravitLauncher/Launcher/security/advisories/GHSA-5g75-477j-2c2f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/GravitLauncher/Launcher"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-22", "CWE-522" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-02T20:49:18Z",
    "nvd_published_at" : null
  }
}