CVE-2025-57330 identifies a Prototype Pollution vulnerability in the web3-core-subscriptions package, specifically in the attachToObject function of versions 1.10.4 and earlier. This package is used to manage web3 subscriptions, which are integral to decentralized applications (dApps) and blockchain interactions that rely on the Web3.js library ecosystem. Prototype Pollution occurs when an attacker is able to inject or modify properties on the Object.prototype, which is the base object from which all JavaScript objects inherit. By supplying a crafted payload to the vulnerable function, an attacker can manipulate the prototype chain, potentially altering the behavior of all objects in the runtime environment. Although the minimum consequence reported is denial of service (DoS), this type of vulnerability can sometimes be leveraged for more severe impacts such as remote code execution or data manipulation depending on the application context. The vulnerability does not require authentication or user interaction, making it easier to exploit if the vulnerable package is exposed to untrusted inputs. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The lack of patch links suggests that a fix may not be publicly available at the time of publication, increasing the urgency for users to monitor updates or implement mitigations.

For European organizations, the impact of this vulnerability depends largely on the extent to which they utilize the web3-core-subscriptions package within their blockchain or decentralized application infrastructure. Organizations involved in fintech, supply chain management, or any sector leveraging Ethereum-based or other blockchain technologies could be affected. A successful exploitation could lead to denial of service, disrupting critical blockchain subscription services, which may impact transaction processing, real-time data feeds, or smart contract event monitoring. This disruption could result in financial losses, reputational damage, and operational downtime. Additionally, if attackers find ways to escalate the impact beyond DoS, such as injecting malicious code or corrupting data, the confidentiality and integrity of blockchain transactions could be compromised. Given the increasing adoption of blockchain technologies in Europe, especially in countries with strong fintech sectors, the threat could have significant operational and economic consequences.

European organizations should first identify whether their software stacks include the vulnerable versions of web3-core-subscriptions (version 1.10.4 or earlier). Immediate mitigation steps include: 1) Restricting or sanitizing inputs to the attachToObject function to prevent malicious payloads from reaching the vulnerable code path. 2) Implementing runtime protections such as JavaScript sandboxing or object freezing to prevent prototype modifications. 3) Monitoring application logs and network traffic for unusual patterns indicative of prototype pollution attempts. 4) Applying strict Content Security Policies (CSP) and other web application firewalls (WAF) rules tailored to detect and block prototype pollution payloads. 5) Engaging with the package maintainers or community to track the release of patches or updates and plan prompt upgrades once available. 6) Conducting code audits and penetration testing focused on prototype pollution vectors within blockchain-related applications. These steps go beyond generic advice by focusing on input validation, runtime protections, and proactive monitoring specific to the nature of this vulnerability.