CVE-2026-25150 is a prototype pollution vulnerability identified in the QwikDev qwik JavaScript framework, specifically in versions before 1.19.0. The vulnerability arises from the formToObj() function within the @builder.io/qwik-city middleware, which converts form field names using dot notation into nested JavaScript objects. However, this function fails to sanitize or restrict dangerous property names such as __proto__, constructor, and prototype. By submitting specially crafted HTTP POST requests with these property names, an unauthenticated attacker can manipulate the Object.prototype, a fundamental JavaScript object from which all other objects inherit properties. This manipulation can lead to prototype pollution, allowing attackers to alter application logic, escalate privileges, bypass authentication mechanisms, or cause denial of service by corrupting application state or triggering unexpected behavior. The vulnerability is remotely exploitable without authentication or user interaction, increasing its risk profile. The CVSS v3.1 score of 9.3 reflects the vulnerability's critical impact on integrity and partial impact on availability, with network attack vector and low attack complexity. The issue was publicly disclosed on February 3, 2026, and patched in qwik version 1.19.0. No known exploits have been reported in the wild yet, but the vulnerability’s nature and ease of exploitation make it a significant threat to applications using affected qwik versions.

For European organizations, this vulnerability poses a serious risk to web applications built on the Qwik framework, especially those using versions prior to 1.19.0. Exploitation can lead to unauthorized privilege escalation, allowing attackers to gain higher access levels within applications, potentially compromising sensitive data and business logic. Authentication bypass could enable attackers to impersonate legitimate users, leading to data breaches or fraudulent activities. Denial of service conditions could disrupt critical services, impacting business continuity and customer trust. Given the widespread adoption of JavaScript frameworks in modern web development, organizations relying on qwik for performance-focused applications may face significant operational and reputational damage if exploited. Additionally, the vulnerability’s unauthenticated remote exploitability increases the likelihood of automated scanning and attacks, necessitating urgent remediation. Compliance with European data protection regulations such as GDPR may also be impacted if personal data is compromised due to this vulnerability.

European organizations should immediately upgrade all instances of the Qwik framework to version 1.19.0 or later, where the vulnerability has been patched. In cases where immediate upgrading is not feasible, implement input validation and sanitization at the application layer to reject or neutralize form field names containing dangerous prototype properties like __proto__, constructor, and prototype. Employ web application firewalls (WAFs) with custom rules to detect and block suspicious HTTP POST requests attempting to exploit prototype pollution patterns. Conduct thorough code reviews and security testing focusing on object property handling and middleware components. Monitor application logs for unusual behavior indicative of prototype pollution attempts. Educate development teams about secure coding practices related to prototype pollution and JavaScript object handling. Finally, maintain an up-to-date inventory of all web applications using qwik to ensure comprehensive patch management and vulnerability tracking.