CVE-2026-78178: jQWidgets Prototype Pollution RCE Vulnerability

CVE-2026-78178 Overview

CVE-2026-78178 is a prototype pollution vulnerability affecting jQWidgets versions up to 24.0.1. The flaw resides in the JQXLite.extend and jqxBaseFramework.extend functions within jqwidgets/jqx-all.js. Attackers can manipulate object prototype attributes through improperly controlled input, enabling remote exploitation without authentication or user interaction. The maintainers closed the associated GitHub issue with the label "not planned," indicating no official fix is planned. The weakness is tracked under CWE-94: Improper Control of Generation of Code.

Critical Impact
Remote attackers can pollute the JavaScript object prototype chain in web applications using jQWidgets, potentially leading to property tampering, logic corruption, and downstream code execution or denial of service.

Affected Products

jQWidgets library versions up to and including 24.0.1
Web applications bundling jqwidgets/jqx-all.js
Front-end components relying on JQXLite.extend or jqxBaseFramework.extend

Discovery Timeline

2026-08-24 - CVE-2026-78178 published to NVD
2026-08-27 - Last updated in NVD database

Technical Details for CVE-2026-78178

Vulnerability Analysis

The vulnerability is a prototype pollution issue in the extend utility functions of jQWidgets. The JQXLite.extend and jqxBaseFramework.extend helpers recursively merge properties from a source object into a target object without validating dangerous keys such as __proto__, constructor, or prototype. Attackers who control merge input can inject properties onto Object.prototype, contaminating every JavaScript object in the runtime.

Because the affected code executes client-side in the browser context, any input path that reaches the extend routines becomes a viable attack surface. Typical injection points include URL parameters parsed into configuration objects, JSON responses passed to widget initializers, and user-controlled options merged into widget defaults. The maintainer response of "not planned" leaves consumers without an upstream patch.

Root Cause

The root cause is missing key validation during recursive object merging inside jqx-all.js. The extend implementation walks source object keys and assigns them into the target without filtering reserved prototype properties, allowing writes to inherited attributes shared across all objects in the JavaScript runtime.

Attack Vector

Exploitation is network-based and unauthenticated. An attacker crafts a payload containing keys such as __proto__.polluted and delivers it through any interface that feeds objects into the vulnerable extend functions. Once pollution succeeds, subsequent code paths that read those inherited properties operate on attacker-controlled values, enabling authentication logic bypass, security check evasion, or gadget-based code execution depending on the host application.

No verified public exploit code has been published. Refer to the VulDB entry for CVE-2026-78178 and GitHub Issue #764 for further technical context.

Detection Methods for CVE-2026-78178

Indicators of Compromise

HTTP request bodies or query strings containing __proto__, constructor.prototype, or prototype[ tokens targeted at endpoints that feed data to jQWidgets components.
Unexpected property values on Object.prototype observed during client-side debugging or runtime inspection.
Anomalous widget behavior such as options being overridden globally across unrelated components on the same page.

Detection Strategies

Perform Software Composition Analysis (SCA) to identify jQWidgets versions up to 24.0.1 in front-end dependencies and bundled artifacts.
Add static analysis rules that flag calls to JQXLite.extend and jqxBaseFramework.extend receiving untrusted input.
Deploy web application firewall signatures matching prototype pollution payloads (__proto__, constructor.prototype) on request parameters and JSON bodies.

Monitoring Recommendations

Monitor content security policy (CSP) violation reports for unexpected script execution originating from pages using jQWidgets.
Log and alert on server-side reflections of client input containing prototype-related keys.
Track browser telemetry for JavaScript errors originating from jqx-all.js that could indicate pollution-induced corruption.

How to Mitigate CVE-2026-78178

Immediate Actions Required

Inventory all applications that ship jqx-all.js and identify user input paths reaching JQXLite.extend or jqxBaseFramework.extend.
Apply input validation that rejects requests containing __proto__, constructor, or prototype keys before they reach client-side merge logic.
Evaluate migrating away from jQWidgets given the maintainer's "not planned" response to the reported issue.

Patch Information

No vendor patch is available. The upstream GitHub Issue #764 was closed as "not planned." Consumers must implement compensating controls, apply a local fork with sanitization, or replace the library. Track the jQWidgets repository for any future changes.

Workarounds

Freeze Object.prototype early in application bootstrap using Object.freeze(Object.prototype) to block pollution writes at runtime.
Wrap or monkey-patch JQXLite.extend and jqxBaseFramework.extend with a sanitizer that strips reserved keys (__proto__, constructor, prototype) before delegation.
Use Object.create(null) for objects passed as targets to extend calls where feasible, eliminating prototype inheritance.
Deploy a web application firewall rule set that blocks prototype pollution payloads in query strings and JSON bodies.

bash

# Configuration example: sanitize extend inputs
# Load this shim before jqx-all.js executes
const RESERVED = ['__proto__', 'constructor', 'prototype'];
function sanitize(obj) {
  if (obj && typeof obj === 'object') {
    for (const key of Object.keys(obj)) {
      if (RESERVED.includes(key)) delete obj[key];
      else sanitize(obj[key]);
    }
  }
  return obj;
}
Object.freeze(Object.prototype);