CVE-2024-39853 Overview
CVE-2024-39853 is a prototype pollution vulnerability affecting adolph_dudu ratio-swiper version 0.0.2, a Node.js package. The flaw resides in the parse function, which fails to sanitize property keys during object construction. Attackers can inject arbitrary properties into Object.prototype, altering the behavior of every object in the JavaScript runtime. Successful exploitation can lead to arbitrary code execution or denial of service (DoS) conditions. The vulnerability is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes. No vendor patch or fixed version has been published in the referenced advisories.
Critical Impact
Remote attackers can pollute the JavaScript prototype chain without authentication, enabling arbitrary code execution or application crashes in applications that consume attacker-controlled input through the vulnerable parse function.
Affected Products
- adolph_dudu ratio-swiper 0.0.2 (Node.js package)
- Applications embedding the vulnerable ratio-swiper module
- Downstream projects that expose the parse function to untrusted input
Discovery Timeline
- 2024-07-01 - CVE-2024-39853 published to the National Vulnerability Database (NVD)
- 2026-06-17 - Last updated in the NVD database
Technical Details for CVE-2024-39853
Vulnerability Analysis
The vulnerability resides in the parse function exposed by ratio-swiper 0.0.2. The function iterates over user-supplied keys and assigns their values to a target object without validating reserved property names. When an attacker supplies keys such as __proto__, constructor, or prototype, the assignment traverses into the base Object.prototype. Every object subsequently created in the process inherits the attacker-controlled property. This behavior can corrupt application logic, bypass security checks, or trigger gadget chains that lead to arbitrary code execution. In simpler cases, polluted properties cause type errors or infinite loops that halt the Node.js event loop, producing a denial of service.
Root Cause
The root cause is missing key validation during recursive object merging inside the parse function. The function trusts input keys and performs direct property assignment without an allowlist or a check for reserved prototype properties. This maps to CWE-1321, Improperly Controlled Modification of Object Prototype Attributes.
Attack Vector
Exploitation requires no authentication and no user interaction when the vulnerable parse function processes attacker-controlled data. The attacker crafts a JSON payload or object containing a __proto__ key with malicious nested properties. Once parsed, the polluted properties propagate to every object in the runtime. A proof-of-concept demonstrating the technique is published as a GitHub Gist PoC Script.
No verified exploit code is reproduced here. Consult the referenced PoC for technical details on payload construction and the impacted call path.
Detection Methods for CVE-2024-39853
Indicators of Compromise
- Unexpected properties appearing on Object.prototype at runtime, discoverable through periodic prototype audits
- Inbound JSON payloads containing the keys __proto__, constructor, or prototype with nested object values
- Node.js process crashes or unhandled exceptions originating from calls to the parse function of ratio-swiper
Detection Strategies
- Perform software composition analysis (SCA) to identify projects declaring ratio-swiper 0.0.2 in package.json or package-lock.json
- Instrument the runtime with Node.js hooks that flag writes to reserved prototype keys during deserialization
- Deploy web application firewall (WAF) rules that inspect request bodies for prototype pollution key patterns
Monitoring Recommendations
- Enable structured logging on the parse entry point and forward events to a centralized log platform for review
- Monitor for anomalous error rates or event-loop stalls in services consuming the ratio-swiper module
- Track dependency inventories continuously and alert on new deployments that include the affected version
How to Mitigate CVE-2024-39853
Immediate Actions Required
- Inventory all applications using ratio-swiper and isolate services that expose the parse function to untrusted input
- Remove or replace ratio-swiper 0.0.2 with a maintained swiper or object-parsing library that validates keys
- Validate and sanitize all input before passing it to any recursive merge or parse routine
Patch Information
No vendor patch or fixed release is referenced in the NVD entry or associated advisories at the time of publication. Consumers should pin to a non-vulnerable alternative or fork the library and apply key validation. Reject any object key that matches __proto__, constructor, or prototype, and prefer Object.create(null) for accumulator objects during parsing.
Workarounds
- Freeze Object.prototype at process startup with Object.freeze(Object.prototype) to block runtime pollution
- Wrap calls to parse with a sanitizer that strips reserved keys before invocation
- Use safe JSON parsers or schema validators such as ajv to enforce strict property allowlists
# Configuration example: audit and remove the vulnerable package
npm ls ratio-swiper
npm uninstall ratio-swiper
# Harden the Node.js runtime against prototype pollution
node -e "Object.freeze(Object.prototype); require('./app.js')"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
