CVE-2026-34523: SillyTavern Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-525j-2hrj-m8fp",
  "modified" : "2026-04-06T17:24:20Z",
  "published" : "2026-04-01T21:40:22Z",
  "aliases" : [ "CVE-2026-34523" ],
  "summary" : "SillyTavern: Path Traversal allows file existence oracle",
  "details" : "### Summary\n\nA path traversal vulnerability in the static file route handler allows any unauthenticated user to determine whether files exist anywhere on the server's filesystem. By sending percent-encoded `../` sequences (`%2E%2E%2F`) in requests to static file routes, an attacker can check for the existence of files (404 if it doesn't exist, 403 means it exists).\n\n### Details\n\nThe vulnerability is in `createRouteHandler` (`src/users.js:947–963`), which backs all user-data static file routes:\n\n```javascript\nfunction createRouteHandler(directoryFn) {\n    return async (req, res) => {\n        const directory = directoryFn(req);\n        const filePath = decodeURIComponent(req.params[0]);\n        const exists = fs.existsSync(path.join(directory, filePath)); // no boundary check here\n        if (!exists) {\n            return res.sendStatus(404);\n        }\n        return res.sendFile(filePath, { root: directory });\n    };\n}\n```\n\n`req.params[0]` contains the raw (percent-encoded) wildcard from the URL. After `decodeURIComponent`, a request path like `/characters/%2E%2E%2F%2E%2E%2FUsers/kirakira` decodes to `../../Users/kirakira`, and `path.join` resolves it outside the intended directory. `res.sendFile` correctly blocks the file from being served (the `send` module's root check returns 403), but `fs.existsSync` had already run, and the 403/404 distinction reveals the result.\n\nAffected routes (they all use the same handler, so they're all affected):\n\n- `/characters/*`\n- `/user/files/*`\n- `/assets/*`\n- `/user/images/*`\n- `/backgrounds/*`\n- `/User%20Avatars/*`\n\n### PoC\n\n```bash\ncurl -o /dev/null -s -w \"%{http_code}\\n\" \"http://localhost:8000/characters/%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2FUsers/kirakira/something\"\n```\n\n### Impact\n\nWhile file contents cannot be read (the `send` module blocks actual delivery), anyone who can reach the SillyTavern HTTP port can check the existence of files on the host filesystem.\n\n### Resolution\n\nThe issue was addressed in version 1.17.0.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "sillytavern"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.17.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.16.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/SillyTavern/SillyTavern/security/advisories/GHSA-525j-2hrj-m8fp"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34523"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/SillyTavern/SillyTavern"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SillyTavern/SillyTavern/releases/tag/1.17.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-01T21:40:22Z",
    "nvd_published_at" : "2026-04-02T18:16:29Z"
  }
}