CVE-2025-62517 identifies a prototype pollution vulnerability in the rollbar.js library, specifically in the merge() function used by rollbar.configure(). Prototype pollution occurs when an attacker can modify the prototype of a base object, potentially altering the behavior of all objects inheriting from it. In this case, if an application calls rollbar.configure() with untrusted or malicious input, an attacker can inject or modify properties on the Object prototype, leading to unexpected behavior or integrity violations in the JavaScript environment. This vulnerability affects rollbar.js versions earlier than 2.26.5 and versions from 3.0.0-alpha1 up to but not including 3.0.0-beta5. The issue was fixed in versions 2.26.5 and 3.0.0-beta5. The CVSS v3.1 score is 5.9, reflecting medium severity, with the vector indicating network attack vector, high attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality impact, high integrity impact, and no availability impact. No known exploits are currently in the wild. The vulnerability primarily threatens the integrity of JavaScript applications using rollbar.js for error tracking if they pass untrusted data to rollbar.configure().

For European organizations, the impact centers on the integrity of client-side or server-side JavaScript applications that utilize rollbar.js for error tracking and logging. An attacker exploiting this vulnerability could manipulate the prototype of JavaScript objects, potentially causing erroneous application behavior, bypassing security controls, or enabling further attacks such as cross-site scripting or denial of service indirectly. While confidentiality and availability are not directly impacted, the integrity compromise can undermine trust in application behavior and error reporting, complicating incident response and debugging efforts. Organizations relying heavily on rollbar.js in customer-facing web applications or internal tools that process untrusted input are particularly at risk. The medium severity rating suggests that while exploitation is not trivial, the potential for damage to application logic and data integrity is significant enough to warrant prompt remediation.

The primary mitigation is to upgrade rollbar.js to version 2.26.5 or later, or 3.0.0-beta5 or later, where the vulnerability has been patched. Until upgrades can be applied, organizations should ensure that no untrusted or user-controlled input is passed to rollbar.configure(), effectively sanitizing and validating all inputs before they reach this function. Implement strict input validation and sanitization routines on all data sources feeding into rollbar configuration. Additionally, conduct code audits to identify any indirect paths through which untrusted data might reach rollbar.configure(). Employ Content Security Policy (CSP) headers to reduce the risk of exploitation via injected scripts. Monitor application logs for unusual behavior or errors that might indicate prototype pollution attempts. Finally, maintain an inventory of JavaScript libraries and their versions to quickly identify vulnerable deployments.