CVE-2026-54756 Overview
CVE-2026-54756 is a prototype pollution vulnerability in Jodit Editor, a WYSIWYG editor written in TypeScript with file and image editing capabilities. Versions prior to 4.12.18 merge user-supplied options into the editor configuration without filtering prototype-mutating keys. The Jodit.configure(options) method and internal ConfigMerge and ConfigProto helpers allow payloads nested under plain-object options such as controls to reach and mutate Object.prototype. Applications that pass user-controlled or partially user-controlled configuration into Jodit.configure() are affected. The issue is categorized under [CWE-1321] and was fixed in version 4.12.18.
Critical Impact
Attackers who control any portion of configuration input can pollute Object.prototype, altering the behavior of every JavaScript object in the runtime and potentially enabling client-side code execution, authentication bypass, or denial of service.
Affected Products
- Jodit Editor versions prior to 4.12.18
- Web applications integrating Jodit Editor with user-controlled configuration
- JavaScript and TypeScript projects consuming Jodit.configure()
Discovery Timeline
- 2026-07-01 - CVE-2026-54756 published to NVD
- 2026-07-02 - Last updated in NVD database
Technical Details for CVE-2026-54756
Vulnerability Analysis
The vulnerability resides in Jodit Editor's configuration merge logic. When Jodit.configure(options) receives an object, the internal ConfigMerge and ConfigProto helpers recursively copy properties from the supplied options into the editor configuration. The merge routine does not filter special keys such as __proto__, constructor, or prototype. As a result, attackers can nest a malicious payload under an existing plain-object option such as controls and reach Object.prototype.
Once Object.prototype is mutated, every JavaScript object in the runtime inherits the injected property. This can alter application logic, bypass security checks that rely on object property presence, or introduce gadgets that lead to cross-site scripting. Applications passing partially user-controlled configuration into Jodit are exposed.
Root Cause
The root cause is missing key-name filtering during recursive object merging. The ConfigMerge helper treats prototype-mutating keys like __proto__ and constructor.prototype as valid property names rather than reserved identifiers. Safe merge implementations must reject these keys or use Object.create(null) for intermediate containers.
Attack Vector
Exploitation requires the attacker to influence configuration input passed to Jodit.configure(). Common paths include configuration values read from URL parameters, form fields, JSON APIs, or third-party integrations. A crafted payload nested under a plain-object option triggers prototype pollution during initialization. No authentication or user interaction is required when the configuration endpoint is exposed to unauthenticated input. Refer to the GitHub Security Advisory GHSA-5957-5c94-3v7w for technical detail on the affected merge paths.
Detection Methods for CVE-2026-54756
Indicators of Compromise
- Requests containing __proto__, constructor, or prototype keys in JSON bodies or query parameters delivered to endpoints that feed Jodit configuration.
- Unexpected properties appearing on baseline JavaScript objects during browser session telemetry or client-side error reports.
- Runtime errors or altered behavior from third-party libraries after Jodit initialization on pages accepting user input.
Detection Strategies
- Inspect application dependency manifests for Jodit Editor versions below 4.12.18 using software composition analysis.
- Add web application firewall rules that flag request payloads containing prototype-mutating keys.
- Instrument client-side code to detect writes to Object.prototype during page load and Jodit initialization.
Monitoring Recommendations
- Log all configuration values passed to Jodit.configure() in non-production builds and review for untrusted sources.
- Monitor Content Security Policy (CSP) violation reports for unexpected inline script execution that may indicate pollution-driven XSS.
- Track npm advisory feeds and the GitHub Security Advisory GHSA-5957-5c94-3v7w for updates.
How to Mitigate CVE-2026-54756
Immediate Actions Required
- Upgrade Jodit Editor to version 4.12.18 or later across all applications.
- Audit code paths that call Jodit.configure() and identify configuration values sourced from user input.
- Sanitize incoming JSON and object payloads to strip __proto__, constructor, and prototype keys before merging.
Patch Information
The maintainers fixed the issue in Jodit Editor 4.12.18. The patch adds filtering for prototype-mutating keys in the ConfigMerge and ConfigProto helpers. Details are available in the GitHub Security Advisory GHSA-5957-5c94-3v7w.
Workarounds
- Freeze Object.prototype at application startup using Object.freeze(Object.prototype) where compatible.
- Deep-clone and validate configuration objects with an allowlist of expected keys before invoking Jodit.configure().
- Replace plain-object intermediates with Object.create(null) for configuration containers to prevent prototype chain access.
# Configuration example: upgrade Jodit Editor to a patched release
npm install jodit@^4.12.18
npm audit --production
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
