GHSA-2m6p-hm3w-6jm3 CVE-2026-46496

HAX CMS: Stored XSS via '<video-player>' component allows arbitrary JavaScript execution and token theft

Medium npm

Severity: 0.0 / 10; Medium · CVSS 4.0
Exploit chance (EPSS): 0.23%; Chance of exploitation in the next 30 days. Higher than 13.90% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-116 Improper Encoding or Escaping of Output; CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Fix: Available; 2 packages have a fixed version

Description

Summary

A stored cross-site scripting (XSS) vulnerability exists in HAX CMS due to improper sanitization of the <video-player> component.

The component allows javascript: URIs in the source attribute, which are executed when the page is viewed. This enables attackers to execute arbitrary JavaScript in the context of the victim’s browser and access sensitive data such as JWT tokens and more.

Details

The vulnerability is present in the <video-player> web component used within the HAX CMS editor.

The application fails to validate or sanitize user-supplied input in the following attributes:

source
source-data

These attributes accept arbitrary URI schemes, including javascript:, which leads to execution of attacker-controlled JavaScript in the browser.

Example vulnerable usage:

<video-player 
  source="javascript:alert(document.domain)" 
  source-type="external">
</video-player>

Because this content is stored and rendered to other users, the vulnerability is classified as a stored XSS.

The root cause is the lack of URI scheme validation and improper sanitization of component attributes before rendering. Because this content is stored and rendered to other users, the vulnerability is classified as a stored XSS.

The root cause is the lack of URI scheme validation and improper sanitization of component attributes before rendering.

PoC

Steps to reproduce:

Log in to HAX CMS as user.
Create a website or any page and switch to the HTML source editor (<>).
Insert the following payload:

<video-player source="javascript:alert('JWT: '+localStorage.getItem('jwt').substring(0,30))" source-type="external"></video-player>

Save the page.

Reload or revisit or send the page.

Result <img width="2468" height="1394" alt="image" src="https://github.com/user-attachments/assets/543bbf69-900d-4e2d-bd6b-0658fb5aa899" />

A JavaScript alert executes. The JWT token is exposed. This confirms arbitrary JavaScript execution in the victim’s browser.

Impact

This vulnerability allows stored XSS leading to:

Theft of JWT authentication tokens
Session hijacking
Full account takeover
Execution of arbitrary JavaScript in victim browsers

If an administrator views a malicious page, this can lead to full CMS compromise.

Attack complexity: Low
Privileges required: Low (any authenticated user)
User interaction: Required

Affected versions

npm

Package	Vulnerable	Fixed in
@haxtheweb/haxcms-nodejs	`< 26.0.0`	`26.0.0`
@haxtheweb/video-player	`< 26.0.0`	`26.0.0`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

@haxtheweb/haxcms-nodejs npm → `26.0.0`

npm

npm install @haxtheweb/haxcms-nodejs@26.0.0

yarn

yarn add @haxtheweb/haxcms-nodejs@26.0.0

pnpm

pnpm add @haxtheweb/haxcms-nodejs@26.0.0

@haxtheweb/video-player npm → `26.0.0`

npm

npm install @haxtheweb/video-player@26.0.0

yarn

yarn add @haxtheweb/video-player@26.0.0

pnpm

pnpm add @haxtheweb/video-player@26.0.0

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Attack vector: Network
Attack complexity: Low
Attack requirements: None
Privileges required: Low
User interaction: Passive
Confidentiality (vulnerable system): None
Integrity (vulnerable system): None
Availability (vulnerable system): None
Confidentiality (subsequent systems): Low
Integrity (subsequent systems): Low
Availability (subsequent systems): None

Weakness

CWE-116: Improper Encoding or Escaping of Output

The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.

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. For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error. Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
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. For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
Architecture and Design, Implementation: 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.
Architecture and Design: In some cases, input validation may be an important strategy when output encoding is not a complete solution. For example, you may be providing the same output that will be processed by multiple consumers that use different encodings or representations. In other cases, you may be required to allow user-supplied input to contain control information, such as limited HTML tags that support formatting in a wiki or bulletin board. When this type of requirement must be met, use an extremely strict allowlist to limit which control sequences can be used. Verify that the resulting syntactic structure is what you expect. Use your normal encoding methods for the remainder of the input.
Architecture and Design: Use input validation as a defense-in-depth measure to reduce the likelihood of output encoding errors (see CWE-20).
Requirements: Fully specify which encodings are required by components that will be communicating with each other.
Implementation: When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.

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-2026-46496

Packages

github.com/haxtheweb/issues

Timeline

May 19, 2026 Published
Sep 10, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-g2g8-95qg-v35h HaxCMS has a stored Cross-Site Scripting (XSS) bypass in its saveNode endpoint	High	Also affects @haxtheweb/haxcms-nodejs
GHSA-9r33-xhw8-4qqp HAX CMS: Denial of Service using Malicious Import Request	Medium	Also affects @haxtheweb/haxcms-nodejs
GHSA-x3x5-7h4h-gwxg HAXcms: Mass Token Exfiltration and Cross-Tenant Hijack	High	Also affects @haxtheweb/haxcms-nodejs
GHSA-jh3h-rpxg-fr36 Stored XSS via <iframe> in HAX CMS allows access to sensitive client-side data and account takeover	High	Also affects @haxtheweb/haxcms-nodejs
GHSA-6c8g-9hfh-pq5h HAXcms: Private Key Disclosure via Broken HMAC Implementation	Critical	Also affects @haxtheweb/haxcms-nodejs
GHSA-q862-gcgq-5m6g HAXcms createSite SSRF Enables Arbitrary File Read	High	Also affects @haxtheweb/haxcms-nodejs
GHSA-3fm2-xfq7-7778 HAXcms Has Stored XSS Vulnerability that May Lead to Account Takeover	Medium	Also affects @haxtheweb/haxcms-nodejs
GHSA-9jr9-8ff3-m894 HAX CMS API Lacks Authorization Checks	High	Also affects @haxtheweb/haxcms-nodejs

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