CVE-2023-0842 identifies a prototype pollution vulnerability in the xml2js library version 0.4.23, a popular Node.js module used for parsing XML into JavaScript objects. The vulnerability arises because the library does not properly validate incoming JSON keys during the parsing process, allowing an attacker to manipulate the __proto__ property of objects. Prototype pollution occurs when an attacker can modify the prototype of a base object, thereby affecting all objects inheriting from it. This can lead to the injection of malicious properties or alteration of existing ones, potentially causing logic flaws, security bypasses, or denial of service in applications relying on the library. The vulnerability is remotely exploitable without authentication or user interaction, as it only requires sending crafted XML or JSON input to the affected application. The CVSS v3.1 score is 5.3 (medium severity), reflecting the lack of confidentiality or availability impact but acknowledging the integrity risk. No public exploits have been reported yet, but the risk remains significant for applications processing untrusted input. The vulnerability is classified under CWE-1321, which relates to improper handling of prototype pollution in JavaScript environments. Since xml2js is widely used in web applications and backend services, the vulnerability can have broad implications if not addressed.

For European organizations, the primary impact is on the integrity of applications that use xml2js version 0.4.23 to parse XML data, especially when processing untrusted or user-supplied input. Prototype pollution can lead to unexpected application behavior, potential privilege escalation within the application context, or bypass of security controls relying on object properties. While confidentiality and availability are not directly affected, the integrity compromise can facilitate further attacks or data manipulation. Organizations in sectors such as finance, healthcare, and critical infrastructure that rely on Node.js applications for data processing could face operational risks and compliance issues if this vulnerability is exploited. Additionally, supply chain risks exist if vulnerable xml2js versions are embedded in third-party software components. The absence of known exploits reduces immediate risk but does not eliminate the need for prompt remediation.

1. Upgrade xml2js to a version where this vulnerability is fixed; if no official patch exists, monitor the project repository or advisories for updates. 2. Implement strict input validation and sanitization to reject or neutralize __proto__ keys or other prototype pollution vectors in incoming XML or JSON data before parsing. 3. Employ runtime security controls such as object freezing or using libraries that prevent prototype pollution. 4. Conduct code audits and dependency scans to identify usage of vulnerable xml2js versions across all projects. 5. Use application-level monitoring to detect anomalous behavior that could indicate exploitation attempts. 6. Educate development teams about prototype pollution risks and secure coding practices related to object property handling in JavaScript. 7. Consider isolating or sandboxing components that parse untrusted XML to limit potential damage.