CVE-2026-50552: Koel Server-Side Request Forgery (SSRF) Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jr4p-4xjh-fwvw",
  "modified" : "2026-07-15T18:21:04Z",
  "published" : "2026-07-15T18:21:04Z",
  "aliases" : [ "CVE-2026-50552" ],
  "summary" : "Koel: Server-Side Request Forgery (SSRF) in radio station creation due to missing validation bail",
  "details" : "Summary\n\nKoel v9.5.0 contains a Server-Side Request Forgery (SSRF) vulnerability in the radio station creation endpoint (POST /api/radio/stations). The url field validation rules are declared without the bail keyword, so the HasAudioContentType rule — which issues HTTP requests to the supplied URL — still executes even after the SafeUrl rule has rejected the URL as pointing to a private/reserved address. Any authenticated, non-admin user can therefore coerce the server into making HEAD/GET requests to arbitrary internal hosts.\n\nThis is a blind SSRF: the response body is never returned to the client, but the two distinct validation error messages form a reliable internal-network reachability oracle.\n\nSeverity\n\nMedium — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N (5.4)\n\nAuthenticated (low-privilege) actor; blind SSRF (no response-body exfiltration). Confidentiality (L) reflects the internal reachability oracle; Integrity (L) reflects state-changing internal endpoints that act on GET/HEAD.\n\nAffected Component\n\n- Version: Koel v9.5.0 (latest release, HEAD b2e9a34, verified 2026-05-30)\n- Endpoint: POST /api/radio/stations\n- Files:\n  - app/Http/Requests/API/Radio/RadioStationStoreRequest.php (missing bail)\n  - app/Rules/HasAudioContentType.php (unguarded HTTP fetch)\n\nRoot Cause\n\napp/Http/Requests/API/Radio/RadioStationStoreRequest.php (lines 25-34):\n\n    'url' => [\n        'required',\n        'url',\n        Rule::unique('radio_stations')->where(function ($query) {\n            return $query->where('user_id', $this->user()->id);\n        }),\n        new SafeUrl(),\n        new HasAudioContentType(),\n    ],\n\nIn Laravel, validation rules within a single attribute run in sequence and do not stop on the first failure unless bail is present or FormRequest::$stopOnFirstFailure is set. Neither is the case here (App\\Http\\Requests\\Request does not override stopOnFirstFailure, and authorize() simply returns true).\n\nFor a directly-supplied private/reserved address (e.g. http://169.254.169.254, http://127.0.0.1:6379, http://192.168.0.1):\n\n1. SafeUrl (app/Rules/SafeUrl.php lines 45-49) calls isPublicHost($uri->host()), fails it, calls $fail(...) and returns. SafeUrl itself does not make a request in this path — good.\n2. Because there is no bail, validation continues to HasAudioContentType.\n3. HasAudioContentType::resolveContentType() (app/Rules/HasAudioContentType.php lines 41-57) issues the request with no IP/host validation of its own:\n\n    private function resolveContentType(string $url): string\n    {\n        try {\n            $response = Http::head($url);              // <-- SSRF\n            if ($response->successful()) {\n                return $response->header('Content-Type');\n            }\n        } catch (Throwable) { }\n    \n        // Falls back to a streaming GET\n        $response = Http::withHeaders(['Icy-MetaData' => '1'])\n            ->withOptions(['stream' => true])\n            ->get($url);                               // <-- SSRF\n        return $response->header('Content-Type');\n    }\n\nThe rule's own docblock (line 13-14) states \"Should be used after SafeUrl to ensure the URL is safe to reach.\" — that assumption is silently violated by the missing bail.\n\nAuthorization Context\n\nThe endpoint is reachable by any authenticated user, not just admins:\n\n- routes/api.base.php line 108 wraps the route group in Route::middleware('auth') only.\n- routes/api.base.php line 268: Route::apiResource('stations', RadioStationController::class).\n- RadioStationController::store() (lines 31-37) carries only #[DisabledInDemo] — no $this->authorize(...), no #[RequiresPlus], no permission check.\n\nReachability Oracle (Information Disclosure)\n\nHasAudioContentType::validate() returns two distinct messages:\n\n- Host unreachable / request throws → \"The url couldn't be reached.\" (line 26)\n- Host reachable but Content-Type is not audio/* → \"The url doesn't look like a valid radio station URL.\" (line 32)\n\nBy diffing these responses an attacker can enumerate which internal hosts/ports are live behind the firewall (internal host discovery and coarse port scanning).\n\nProof of Concept\n\nAs any regular authenticated user:\n\n    POST /api/radio/stations HTTP/1.1\n    Host: koel.example.com\n    Authorization: Bearer <regular_user_token>\n    Content-Type: application/json\n    \n    {\n      \"name\": \"probe\",\n      \"url\": \"http://127.0.0.1:6379\"\n    }\n\n- If the internal service answers → \"The url doesn't look like a valid radio station URL.\"\n- If nothing is listening → \"The url couldn't be reached.\"\n\nThe server has now issued a HEAD and a streaming GET to 127.0.0.1:6379 despite SafeUrl having rejected it.\n\nImpact\n\n- Blind SSRF: server-side HEAD/GET to attacker-chosen internal addresses. The response body is never returned to the client, so this cannot directly exfiltrate content (e.g. cloud-metadata bodies).\n- Internal reachability oracle: reliable live-host / open-port discovery via the two distinct error strings.\n- Side-effect requests: any internal endpoint that performs a state-changing action on GET/HEAD can be triggered.\n\nNote on scope: because SafeUrl calls $fail() for a private host, the overall request validation fails (Laravel aggregates all rule failures; a single failure yields a 422), so RadioStationController::store() never runs and no station is persisted. The impact is therefore limited to the out-of-band HEAD/GET requests issued by HasAudioContentType during validation, plus the reachability oracle — it does not chain into a stored station or into the authenticated radio stream proxy via this path.\n\nRecommended Fix\n\nAdd bail so HasAudioContentType only runs after SafeUrl passes, restoring the rule's documented precondition:\n\n    'url' => [\n        'required',\n        'url',\n        'bail',\n        Rule::unique('radio_stations')->where(/* ... */),\n        new SafeUrl(),\n        new HasAudioContentType(),\n    ],\n\n(Place bail before SafeUrl/HasAudioContentType; the unique check is local DB only and safe to keep ahead of it if preferred.)\n\nDefense in depth\n\nHave HasAudioContentType::resolveContentType() re-validate the host with Network::isPublicHost() (or reuse Network::isSafeUrl()) before issuing any request, so the rule is safe regardless of ordering. The same Network helper is already used by PodcastService for enclosure URLs.\n\nRelationship to CVE-2026-47260\n\nCVE-2026-47260 addressed SSRF via podcast episode enclosure URLs; the current code guards that sink in app/Services/Podcast/PodcastService.php (line 143) with Network::isSafeUrl(). The radio-station path relies instead on the SafeUrl validation rule, but the missing bail lets the adjacent HasAudioContentType fetch run anyway — leaving an SSRF reachable from the same class of untrusted, user-supplied URLs. I have not been able to confirm the exact upstream fix commit for CVE-2026-47260 from the release tarball, so I am presenting this as an independent finding rather than asserting it is the same code change.\n\nDisclosure\n\n- 2026-05-30: Identified via source review of v9.5.0 (b2e9a34).\n- Verified entirely by source inspection (route middleware, controller, FormRequest base class, and both validation rules). No live PoC was executed against a third-party host.\n\nIf the maintainers agree this is a distinct issue, would you consider requesting a CVE identifier for it through GitHub Security Advisories? Happy to provide any further detail or testing.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "phanan/koel"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "9.7.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 9.7.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/koel/koel/security/advisories/GHSA-jr4p-4xjh-fwvw"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-50552"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/koel/koel/pull/2549"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/koel/koel/commit/5f6ce2cefd08f437a269236b677ad971517ccbb6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/koel/koel"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/koel/koel/releases/tag/v9.7.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-15T18:21:04Z",
    "nvd_published_at" : "2026-06-12T20:16:47Z"
  }
}